After you have collected 3 Cream Soda barrels & placed them in your fishing net, you go down to where the 4th barrel is located but don't collect it... focus on the coins you are going to get!
Go past the 4th barrel and head towards the big fish (called the Mullet) swimming in the gap between the rocks. Get ready! This part's tricky!
To get through the gap, you need to be patient. Stick to the top of the rock and keep on pushing past the fish. Remember to keep an eye on your air levels!
Once you are past the Mullet, go up to get air if you need to, then go down, all the way. You will find a big pile of coins! WOW! Use your grabber to collect the coins...
BUT be quick!!! Otherwise the crab (called Klutzy) will take them all before you can
