The craft pictured above isn't a sea plane. It's an ekranoplan, or sea skimmer. And it's a very curious vehicle.
I first read about the ekranoplan in one of William Gibson's novels. Gibson is usually three steps ahead, and one step diagonal, of most writers and I admire how he integrates wonderfully obscure technology into his work. But in this case, I had trouble mentally picturing a vehicle that skimmed above the water.
An ekranoplan isn't a hovercraft. A hovercraft uses fans to float on a cushion of air. And it isn't a hydrofoil, which is more like a vehicle on skis. An article in Global Aircraft gives an excellent example. If you've ever watched a seabird cruise just above the surface of the water while rarely moving its wings, you've witnessed the 'wing in ground' effect. A winged vehicle running very close to the surface benefits because the gap between the wing and the ground is small enough for the air to be compressed.
While the idea of ekranoplans goes back to the 1930s, the Soviet Union was the first to deploy them for military use from the 1960s through the 1980s. The Soviets developed different models for use as transports, cargo carriers and anti-submarine craft in the Caspian Sea and the Black Sea. One of the appealing military virtues of the ekranoplan was that it flew so low it was difficult for radar to detect. The largest Soviet ekranoplan, the KM, weighed 540 tons when loaded and could travel at over 400 kilometers (or 249 miles) per hour.
The amazing thing about ekranoplans is that they can carry heavy cargo at high speed but use less fuel than an airplane traveling the same distance and speed. This is why I think the design may be reappear in the near future. An article in Gizmohighway pointed out that small ekranoplans were used in commercial trials in the Bahamas and the USA in the mid-1990s.
With the costs of fuel rising, I think companies might look at the ekranoplan as a way to move cargo, and perhaps people, across large lakes and inland seas. So someday we may all have a chance to ride on one of these curious vehicles.
(First pic is from olbri2007.narod.ru. Second is from englishrussia.com. The explanation of wing in ground effect is from Wikipedia.)