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Modern superyachts have become oversize toy chests, with new technologies and designs pushing the boundaries of aquatic recreation well beyond paddling around in a kayak or careening down a giant inflatable slide. From piloting your own personal sub beneath the waves to foiling across the surf, the following high-tech playthings represent a sea change in open-ocean fun.

Arguably the most technical personal watercraft available, Kawasaki's Ultra 310LX , starting at $20,299, features glowing bow "eyes" that are actually LED daytime running lights. Launch Control mode lets the electronic-control unit determine the perfect trim in various acceleration scenarios, and the Bluetooth sound system doubles the standard offering with four speakers. The most unusual feature? A rearview camera, which comes in handy when navigating a crowded marina.

The new Lift4 electric foiling board, starting at $11,995, has advanced features designed to accommodate most rider profiles. The Lift Full Range Battery offers ride times of up to 2.5 hours, and the carbon-fiber masts are paired with a sophisticated modular propulsion unit. The pistol-style controller has a customizable color screen, a milled-titanium trigger, and GPS to track speed and distance. Personalization ramps up with 12 color options, including metallic finishes.

The most powerful of the Seabob F series comes with seven power levels to deliver everything from a leisurely glide to a full-throttle dive. Detailed in a rich-looking chrome, or a stealthier all-black presentation on request, the $17,780 electric craft also has a high-definition-camera system, including one on the bow and a second "selfie" cam on the information display. Twin rear fins assist with aggressive turns while adding to the sleek design.

With a footprint similar to a pair of Jet Skis, the Nemo submersible was designed for transport on any yacht in the 100-foot-and-above range, though it's compact enough to be trailered behind a large SUV or pickup. Allowing one to travel in covert-operative style, the Nemo comes in single- or double-seat configurations (priced at about $588,000 and $637,000, respectively) with both versions able to reach a maximum depth of 330 feet. The battery-powered propulsion lasts up to eight hours, though range is, of course, depth-dependent.

Bote's Flood 12’ Paddle Board is stable, easy to carry, and the perfect all-rounder in the stand-up paddleboard market. Beyond its vibrant aesthetics, the board (starting at $1,699) has a planing hull that glides though chop and allows for precision turns. The "stash pod" at the stern keeps drinks cool and valuables safe, while the optional Tackle Rack is designed to keep your gear high, dry, and out of the water.

Windsurfing's sell-by date seemed to have passed in the 1990s, until Starboard resurrected the sport with the iQFoil, capable of cruising from 5 to 35 knots on its carbon-fiber foil. The iQFoil, starting at $10,299, is so advanced that it will be the official windsurfer of the 2024 and 2028 Olympics, with carbon-reflex technology that enables riders to adjust and control the craft in different wind conditions.

A four-seat semisubmersible, the Jet Shark is aptly named thanks to its apex-predator speed and agility. The craft combines a cushy, air-conditioned cabin with a helm console that resembles a fighter jet, and its 420 hp Kodiak marine engine even gives it the ability to leap out of the water. With an option-dependent price between $200,000 and $300,000, the machine is in its final testing phase.