two prototype aircraft were tested off the coast of haikou , in the hainan province of china .
the cyg-11 plane can reach a top speed of 155mph and boasts a maximum range of 930 miles .
the super-efficient craft uses increased lift and reduced drag from its wings to fly 16ft -lrb- 5m -rrb- above thewaves .
engineers hope the groundbreaking aircraft could be used on ` motorways of the sea ' in the future .