Crouch jump just before the water reaches its maximum. Wait until Samus reaches the peak of the jump; then in quick succession press down and then forward (or diagonal down-forward). This only works as a way out of the water on the right side.

The problem with pressing down pre-maturely is that it shrinks Samus' hitbox vertically, causing Samus to escape the water, which results in a shortened jump height because of the larger vertical acceleration that applies when Samus is in air physics.