Are you considering an underwater jet ski? Our guide explains how underwater jet skis work and compares different models, including the market-leading SEABOB.
If you’ve ever explored the underwater world, you’ll know that it takes a lot of effort and planning to dive beneath the surface and see what’s on the seabed.
But what if there were a way to quickly plunge underwater with minimal effort whenever you want?
Now there is. Enter the underwater jet ski.
If you remember James Bond in Thunderball motoring around underwater, you’ll have an idea of just what an underwater jet ski can do.
Now imagine a modern underwater jet ski that is sleeker, more compact and powerful, and you’ll be closer to modern design.
Our guide takes a look at the incredible ability of underwater jet skis, and some of the top-selling models on the market.
What’s an Underwater Jet Ski?
An underwater jet ski is a generic term that’s used for a vast range of craft that are capable of diving below the surface.
Used in swimming pools, lakes and in the ocean, these motorized devices are the ultimate diving companion, offering a greater experience without the exertion.
Although they’re described as underwater jet skis, they don’t look anything like their above-water namesake. You won’t be sitting on this craft, or even kneeling, and they’re much smaller and more compact.
The underwater jet ski is made up of two handles and a central console which the diver grasps onto while they move. The body position will be just the same as swimming, except the underwater jet ski will be making all of the effort.
Switches typically located near the thumb allow the device to be switched on and off, and in most models, there are also buttons that increase or decrease speed.
Some are specifically designed to be used by more experienced divers, but there are many models suitable for novice divers too.
One of the determining factors is the speed. The more basic models offer a slower speed and less power. If you just want to swim leisurely or take your snorkeling to the next level, this is probably more than sufficient.
However, if you want to get deeper down you’ll want a craft that can get you into the water more quickly. This is where greater speeds and more power in the engine will come in useful.
In the market you’ll find models which offer a top speed starting from around 2mph and going right up to just under 14mph. The SEABOB is the fastest model in the market right now, offering top speeds of approximately 13.7mph.
Battery life is another factor; if you run out of power, you’ll find yourself swimming rather than being towed.
That may be fine, but if you’re at a deep level and only have limited breath left, having to suddenly exert yourself to get to the surface may be a struggle.
Batteries normally last 60-90 minutes and take several hours to charge up. Models with inexpensive battery replacements make it possible to carry around two fully charged batteries to extend your dive.
You can either use an underwater jet ski to move around more quickly near the surface or to dive below. Depths of 15 feet to up to 100 feet is the normal range, but it is possible to find some models that will go deeper.
Typical Uses
Sea scooters and underwater jet skis can be used for a vast range of water-based activities, and aren’t just the property of those who are more experienced divers.
There is a great range of models which are suitable for different purposes, so it’s important to pick the right one for your needs.
Smaller underwater jet skis can be used in swimming pools for recreational fun. These designs are lighter, smaller and have lower speeds to make them usable in the smaller area.
Some of the larger pool scooters can also be used in the ocean to complement snorkeling.
Even the models which are primarily intended for use in the ocean or larger bodies of outdoor water vary significantly. Some designs are better for shallow diving and have relatively low-powered engines.
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Others are used for deeper diving and offer advanced features such as inbuilt cameras.
Underwater jet skis remove the effort from moving around in the water and make it easier to move quickly. They’re not just for fun and zooming around either; they’re a useful tool for advanced divers who need to carry a lot of equipment.
From snorkeling and carrying out fun acrobatics to deep diving and assisting with diving photography, underwater jet skis take water-based activities to the next level.
If you want to go faster, you should check out my article on enclosed underwater jet skis.
How Do They Work?
Regardless of whether the underwater jet ski is going to be used in a pool or in the ocean, the working mechanism is exactly the same.
It’s a very eco-friendly type of device and you don’t need to worry about any environmental impact due to emissions.
In a similar way to a regular jet ski pr personal watercraft, an underwater model relies on water displacement to steer and move. An encased propeller helps to keep everyone safe and prevent injuries to body parts.
There are also designs that have an extra mesh and prevent little fingers from poking through!
The propulsion system relies on power to suck in the water, so each jet ski has a battery to drive the motor. If there is no power running through the system, you won’t be towed along and instead will have to swim with the device through the water.
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Most models allow the speed of the engine to be increased, which in turn increases the amount of water being pushed through. This provides more thrust and greater speeds.
The weight of underwater jet skis can vary significantly, from just a few kilos for smaller models right up to 35kgs for more advanced designs. However, when in the water, the scooter won’t sink as it’s been carefully balanced to be buoyant.
Some models automatically adjust the buoyancy while others allow extra weights to be added or removed to assist with diving.
Popular Underwater Jet Ski Models
These are the only manufacturers worth looking at in 2021. We’ll start with the most expensive and fastest option out there.
SEABOB
When it comes to underwater jet skis, undoubtedly the leader of the pack is the SEABOB.
Described by some as the Ferraris of the marine world, SEABOB is a luxury design that is versatile and high-performing.
They have a range of different models, but all of these come with a luxury price tag to match.
The SEABOB F5 is the entry level model, but make no mistake there’s nothing basic about this craft.
Compared to some others on the market, even this SEABOB offers an intense diving experience that’s unforgettable.
Weighing in at 29kg, the F5 is made from lightweight carbon elements, completed with ceramic coatings and using precious metals with a known resistance to corrosive saltwater. Each model is handcrafted to meet meticulously high standards.
You can hit up to 131 feet when you’re diving with the SEABOB, and it has a safety shut-off so you won’t accidentally go too deep.
You can pre-set the maximum dive depth which is useful if the unit is being used by less experienced or younger divers.
There are four power levels that enable you to reach a top speed of 8.08mph while under the water, or the slightly faster 8.70mph while above water.
It’s just as much fun skimming along the surface as it is diving deep, and the SEABOB F5 can offer you the ability to enjoy both.
Their patented E-Jet Power System provides an almost whisper-quiet experience so you won’t spook the surrounding marine life while you temporarily join their world.
The SEABOB F5 S is the next model in the set, offering the same depths but significantly increased speed. Upgrading to this model will offer six different speed levels which go up to 12.4mph underwater.
The thrust also increases to 680N, up from 480N on the basic F5. It is slightly heavier though, weighing 34kg.
The SEABOB F5 SR is the daddy of them all with a whopping top speed of 13.7mph, available in seven different increments.
It doesn’t go quite as deep, up to 120 feet, but if speed is your main aim, you won’t find anything faster than this other than fish or a full-blown submarine.
The F5 SR also features two cameras that allow you to film the water in front of you, as well as take selfies and upload them via WiFi. If you’ve always wanted to post an underwater snap directly to social media, the SEABOB F5 SR is what you need.
The weight increase is relatively low, coming in at just 1kg more than the F5 S at 35kg. Thrust increases to 745N and it’s capable of a meaty 6HP (compared to 3.3HP and 5.3HP for the F% and F5 S).
Pros:
- An all-inclusive design offers everything a diver could want
- Suitable for shallow and deep dives
- Outstanding speed for even pro divers
- Can be ordered with a pre-installed camera
- Powerful and agile jet system
- Clear display screen with full metrics
Cons:
- The most expensive model around
- Heavier than other underwater jet skis
- F5 S and F5 SR not suitable for use in small pools
Yamaha
Yamaha has a range of underwater jet skis, which is refers to as sea scooters. These vary between the more basic models designed for use in pools to powerful scooters which can dive at depth and speed in the ocean.
The Yamaha 500Li is one of their advanced models which offers incredible opportunities to explore in open water.
As the name suggests, the Yamaha 500Li has 500 watts of power which enables it to reach speeds of up to 4.35mph. There’s a three-level rotational speed control which allows divers to select how fast they want to move.
A high-performance lithium battery is lightweight and powerful, providing divers with more time to explore the sea bed and less time in transit. This provides up to 90 minutes of diving with normal use, up to a depth of 131 feet.
The handles have an ergonomic design with the thumb triggers placed in a comfortable position. There are also armrests which are useful if you plan on going for a longer, more leisurely dive.
The buoyancy automatically self-adjusts but you can add extra weights if you aren’t able to dive quickly enough.
There is no doubt that the 500Li is a premium model and offers a well-thought out design that’s geared towards professional and serious divers.
The top speed is a bit noisy but you’re unlikely to be using this very often, as it’s almost impossibly fast for a leisurely swim.
If you’re considering splashing out on a diving treat, here’s what you’ll need to weigh up:
Pros:
- Comfortable, ergonomic design for extended use
- High-quality battery
- Capable of very fast speeds
- Dives to deep depth
- Long swimming time per charge
Cons:
- Very expensive compared to other underwater jet skis
- Noisy at top speed
Sea Doo
Sea Doo is one of the top names for regular jet skis, so it’s perhaps unsurprising that they’re one of the leaders for underwater craft too.
Their top model is the Sea Doo GTI, a powerful beast that’s suitable for use in the ocean, and not just the placid waters in a swimming pool.
Extremely powerful, the GTI can manage speeds up to 2.5mph and has a battery life of up to one hour in open water.
It can officially dive to a depth of 100ft, but some users have reported taking it down to 115ft, making it suitable for deep diving adventures.
Disappointingly, there’s no camera mount but it is possible to mount a depth gauge or compass on the nose cone to help you keep track of your location.
Adjustable buoyancy is another plus, allowing it to be used just as effectively for snorkeling as deeper dives.
Sea Doo’s underwater scooters may not be as popular as their PWC but they’re still awesome pieces of kit.
Pros:
- Speedy
- Versatile enough for deep diving and shallow snorkeling
- Lightweight and compact
- Can cope with strong currents
- At low speeds can be guided with one hand
- Replacement batteries are cheap so it’s economical to buy spares for longer dives
- Adjustable buoyancy levels
Cons:
- Will not pull more than one diver
- Battery wears out quickly and usually needs replacing after one season
- No camera mount
- Two hands needed to control it at faster speeds
Subwing
If you’re on a budget, there’s a low-cost alternative to underwater jet skis courtesy of the Subwing. With no motor attached and relying entirely on the power of the boat, it’s a cheap and easy water to get more speed underwater without breaking the bank.
The Subwing consists of two separate “wings” which are attached via a tow rope to the boat in the water ahead. The boat moves slowly through the water while the diver holds onto the two joined wings.
The diver still has complete control of their movement underwater. The two wings move independently of each other; tilting them downwards allows a deeper diver, while upwards brings you back up to the surface.
The Subwing should be towed at a gentle pace of 2-4 knots, a speed which provides an exhilarating experience below the surface, in return for minimal effort.
As the boat is only required to go at a slow speed, it means that you don’t need an expensive vessel – dinghies, jet skis or any type or motorboat will suffice!
At less than a quarter of the price of even basic motorized underwater jet skis, Subwing provides an economical alternative.
In fact, you could buy more than ten sets of Subwings for the same cost as a single, top of the range SEABOB F5 SR. If you’re thinking of purchasing Subwings, here’s what you should consider:
Pros:
- Easy to master and use, even for novice divers
- Control your own depth of dive
- Multiple Subwings can be used with a single motorboat
- Cheap to purchase and with no expensive parts to replace
- No need to rely on a battery
Cons:
- You have less freedom and control than with motorized models
- Tow rope has to be purchased separately
- Maximum depth is limited to 10 meters and considerably less for inexperienced divers
Conclusion
Underwater jet skis, or sea scooters as they’re called by some manufacturers, provide an extra dimension to snorkeling and diving.
You don’t need to be an expert swimmer to use an underwater jet ski and they allow you to dive while expending far less energy.
It’s fair to say however that there’s an enormous price range between the different models and very different capabilities too. If you’re hoping to deep dive in the ocean, there’s no point in buying a lightweight model that can only handle shallow water.
If you have regular access to your own motorized craft and plan on using the jet ski just for underwater acrobatics and snorkeling, the Subwing might be a good pick.
It’s simple and safe to use and is much more economical for large groups to play in the ocean together.
However, if you’re a more experienced diver and plan on diving to depths of 100 feet or more, the more expensive models have many more useful features.
It is possible to navigate these depths without splashing out for top of the range models like the SEABOB, but it will be a compromise.
Not many will be able to afford to buy the SEABOB without doing some serious savings, but the power, durability and extra features make it something very special. While many other models offer plenty of fun, the SEABOB really is in a class of its own.
