Kill all of the enemies and leave drops uncollected so that the Zoas will not be in the way. Stand on the edge of the sand and place a Bomb or Power Bomb and wait briefly before entering the sand. Let the explosion push Samus up for a few frames before simultaneously jumping and aiming down. Then move left to down-grab onto the morph tunnel ledge. Jumping too early can lead to a softlock but jumping too late usually exits the sand safely.