What is "aquaplanes"

Usage examples of "aquaplanes".

At high tide in the afternoon I watched his guests diving from the tower of his raft, or taking the sun on the hot sand of his beach while his two motor-boats slit the waters of the Sound, drawing aquaplanes over cataracts of foam.

They were very much like the aquaplanes commonly towed behind motorboats, but much cruder, and designed to go under rather than remain on the surface.