How to complete Whale Stage in Super Mario Land 2: 6 Golden Coins.
How to Clear Whale Stage
Go to the right, and make sure not to jump and hit the ribs sticking down from above. An Aqua Goomba will walk toward you from the right. After the Aqua Goomba, get the coins near the ceiling. There is another Aqua Goomba after the coins.
Next, there is a rectangular platform made of a spongy substance that you will slowly sink down through, but you can press the jump button to go back up, like the tree sap in Tree Zone. Make sure not to fall onto the ribs below. Get the coins and hit the ? Block to get a Carrot.
Next, there are some small ribs that move up and down from the ceiling, so make sure not to let them hit you. After the small ribs, there is an Aqua Goomba.
Next, there are two large ribs in the ceiling, then four small spongy platforms. Some of these platforms have coins beneath them, so sink down through the platforms to get the coins. The third platform has a Paragoomba after it.
After that, hit the Midway Bell.
Next, there is an Aqua Goomba on top of three ? Blocks. The rightmost ? Block in this group contains a Super Mushroom or Fire Flower. Beware of the Honebon beneath the ? Blocks.
The next set of three ? Blocks also has an Aqua Goomba on top. These ? Blocks just contain coins.
After the water, there is a Koopa Troopa. Then there is an Aqua Goomba. Next, you find an area with large ceiling ribs, some of which have coins between them, and a Koopa Troopa and two Aqua Goombas.
Next, there is a pool of water surrounded by spongy walls. There are coins and large ribs above and below the pool of water. There is a ? Block that contains a Super Mushroom or Fire Flower, but watch out for the Honebon that swims back and forth beneath it.
Just after the Honebon, there are two ribs in the ceiling that don't have any coins between them, but if you jump up when you're to the right of the left rib, you reveal a Hidden Block that contains a Moneybag.
Go to the right and get the remaining coins, then go to the right to get past the pool of water.
There is a Paragoomba and a Koopa Troopa, then the pipe to the final boss of Turtle Zone.
Octopus
Octopus will create smaller octopodes. If Mario is to the left of a little octopus when it appears, it will keep moving to the left even if Mario goes to the right of it. If Mario is to the right when it appears, it keeps going to the right. Each small octopus will move slowly upward if Mario is above it, or downward if Mario is below it. The small octopodes can't go farther down than Mario's head, so you can dodge them by crouching if you're tall, or just staying on the ground if you're small. If you try to stomp on a small octopus, you will just bounce upward. The small octopodes can't be hurt.
You can jump up out of the water, but the darker colored blobs that hang from the ceiling are obstacles that you will bounce off of, so keep that in mind.
Dodge the little octopodes and stomp on the big Octopus or throw fireballs at it until it is defeated.
After the Battle
After you defeat the Octopus, the Turtle Coin comes out of the octopus pot and goes into the gate at Wario's Castle. An "X" flag appears above Turtle Zone in the map (but you can still redo the levels there if you wish).
If you got all six golden coins, you can now proceed to Wario's Castle in the middle of the map. The entrance accessible from the southern part of the map, near Tree Zone.
Now you can go to any of the other zones:
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