Once in the tunnel watch out for crawlers and drifters. Drop bombs to take out the crawlers, watch out cause it is possible to also take out the ground below. So roll to safety. If you do fall down to the tunnel below, you can easily drop a bomb to make Samus hop back up before the platform reappears. Keep going right until you reach a room with a drifter trapped on the bottom. Unlike the other rooms where you can bomb the floor to drop, here
you need to shoot up. You can keep jumping til the platforms reappears if you want, it will lead to a room with a high door that is unreachable. Plant bombs to blow up the ground below and fall back down. Continue going right, it was worth checking to know what is there and also to keep it in mind. Ahead, you will run into some hornet's nests. Get pass them to collect another missle upgrade. This will add 5 more missles to your total
capacity. After acquiring the Missle Upgrade, keep moving right til you reach a dead end. Don't let your eyes fool you, you've haven't reach the end. Simply just shoot up like in the screenshot on the left. Jump up and keep going right. You will reach another room with a sweeper inside, take him out before entering the room. Curl up into a sphere and roll to the right corner, plant bombs to make Samus hop and hold right to enter the secret tunnel.
