What plane can land the slowest on the water? What plane can land on the choppiest water? Is there a way to land between the waves?
Depends on how bad is the sea state, but the general technique for seaplanes is to land parallel to the swell, preferably on top of a wave:
When landing on a swell system with large, widely spaced crests more than four times the length of the floats, the best landing heading parallels the crests and has the most favorable headwind component. In this situation, it makes little difference whether touchdown is on top of the crest or in the trough.
If forced to land against the swell, it is recommended to land on the backside of the wave:
If crosswind limits would be exceeded by landing parallel to the swell, landing perpendicular to the swell might be the only option. Landing in closely spaced swells less than four times the length of the floats should be considered an emergency procedure only, since damage or loss of the seaplane can be expected. If the distance between crests is less than half the length of the floats, the touchdown may be smooth, since the floats will always be supported by at least two waves, but expect severe motion and forces as the seaplane slows. A downswell landing on the back of the swell is preferred.