Underwater scooters are nothing new, although most of them are devices which users must hold in front of themselves. The Seakool D2 is different in that it's worn around the waist, keeping the user's hands free and their view unobstructed.
Currently the subject of an Indiegogo campaign, the D2 is made by Chinese drone manufacturer HighGreat.
It incorporates what is essentially a big belt that's equipped with a pushbutton control unit and a removable lithium-polymer battery. Extending down from the belt on either side are two electric thrusters, which are strapped to the user's thighs.
Each thruster delivers 29 lb (13 kg) of thrust, taking the user to a claimed top speed of 4.5 mph (7.2 km/h). One charge of the battery reportedly allows them to maintain that speed for 33 minutes.
There are two lower speeds, which are selected via the controller. One lets the user cruise at 3.4 mph (5.5 km/h) for up to one hour, while the other takes them to 2.2 mph (3.5 km/h) for two hours.
All of the quoted runtimes are for a 176-lb (80-kg) user, and they can be doubled by opting for a second battery. The whole setup – with the standard single battery – is said to tip the scales at 13 lb (6 kg). It's rated to a maximum depth of 65 ft (20 m).
Assuming the Seakool D2 reaches production, a pledge of US$998 will get you one. The planned retail price is $1,689. It's demonstrated in the video below. Prospective backers might also want to check out the successfully Kickstarted SubCruiser, which incorporates two thigh-worn thrusters connected to a backpack unit.
I suspect there's some good reasons why they aren't (can't?).
I'd want a system like this to be able to supplement my own swimming efforts not just provide complete propulsion.