Kainui is one of a pair of double planets circling a pair of binary stars. Mike Hoani has come there to study the languarge of the colonists. But Kainui is an ocean planet, covered in water 1700 miles deep, with no solid ground anywhere. The population is scattered in cities on floating artificial islands with no fixed locations. The atmosphere isn't breathable, and lightning, water-spouts, and tsunamis are constant. Out on the great planetary ocean, self-sufficiency is crucial, and far from any floating city, on a small working-family ship, anything can happen. Mike's academic research turns into an exotic nautical adventure unlike anything he could have imagined.