How do you go under the bridge on Skullduggery Island on poptropica?

Answer 1

On the side of where you meet the girl, click her and she'll tell you she should have saved her coin. Go all the way down to where the ruined corn is, turn left and keep going, it'll give you the option to go left, the doubloon is there you just walk (or should I say swim) and then you go back.

Answer 2

You go to the far left of the screen (under the skull) and climb up the ledges until you reach the cannonry. Then you can climb up to the Corsair Cannonry and hire the man who once worked for Crawfish for 20,000 doubloons (Sheesh...I can't even get more than 700...) Then you climb up onto the mast and take the cannon making kit from beneath the flag. The kit works on any of the four cannons but the one on the bottom left is the most important. On the way back down to the ship, push the barrel of explosives into the water below the skull. Position the barrel under the Gold Tooth. If you fire the cannon and hit the barrel, the blast shakes loose the Golden Tooth and reveals the map piece. Happy sailing! ;)