If you're considering purchasing a personal submersible for your yacht, there is only one man in the world you'd want to build it. His name is Graham Hawkes, and he's been designing and producing submarines – some 60 custom underwater vehicles alone – for many decades. His most famous work remains the DeepFlight Challenger, which the late Steve Fossett commissioned and Richard Branson subsequently funded to race James Cameron to the bottom of the Marianas Trench, but there have been plenty of others.

The Super Falcon is – as far as these things go – a far more practical manned submersible. Currently for sale on a custom basis and available for weeklong charters, this underwater plane doesn't yet take commercial passengers due to regulatory constraints, but Hawkes's company does offer underwater pilot training courses for its clients. And Red Bull co-founder Dietrich Mateschitz is considering providing rides in his Falcon to guests at Laucala, his private island resort in Fiji.

Nearly 21 feet long, the Super Falcon has two cockpits and resembles a tiny, futuristic plane. Unlike other submersibles, which troll the ocean floor, this one flies above it. As a pilot, you can perform rolls, explode out of the surface like a space-age whale, and sidle up to great white sharks, who, Hawkes says, tend to view the sub as one of their kind. Want to go deeper? No problem. Follow whales' songs 500 feet down and circle pods of resting humpbacks.

"If you're doing advanced maneuvering, the experience can be intense and breathtaking," says Adam Wright, president of DeepFlight. "But if you're doing it to view the underwater community, it's relaxing and magical."

More information: Chartering a Super Falcon from DeepFlight starts at about $50,000 a week.