Contact the water at the correct pitch attitude and touchdown speed.

Bottom line

Use flaps, throttle, and pitch to control the glidepath and establish a stabilized approach at the recommended approach airspeed. In general, make the touchdown at a somewhat flatter pitch attitude than usual. Reduce power as the seaplane settles into the water, and apply back pressure as it comes off the step to keep the float bows from digging into a wave face.