Water Station is the first level in Super Mario Pirate Adventure. It features a shoreline with many water machines. It features Petey Piranha as a boss. This is the beginner level of the game. It has some resemblances to Bianco Hills from Super Mario Sunshine.
Here is the soundtrack for this level.
In your first mission in the game, you must battle a boss! Explore the area, get coins, talk to the Piantas and learn the area well! When you are ready for completion, head over to the big watermill. Petey Piranha will be waiting for you. To defeat him, there are only two characters possible. Mario and Bowser Jr. With Mario, you can defeat him like how you did in Super Mario Sunshine. Spray water in his mouth, and ground pound on his belly. With Bowser Jr, when he is about to project vomit, somersault right into him. Do that 3 times with either character, and get Power Star #1!
Breaking into the Water System
For this level, you can use any character. So, follow the same path you did to get to where Petey Piranha was. Beside it, there will be a big turny thing. Grab a Bob Omb, and shoot it at it. That will break it up, and a Banzai Bill will show up. He will challenge you in a race similar to Piranha Plant Slide from Mario Kart 7 (except you won't have a kart). When you win, he will give you Power Star #2.
For this level, you have 20 seconds to run to Petey Piranha and defeat him. You can collect + clocks on your way. You can't use Mario, as his powers take too long, and regardless of the situation, it is impossible to beat Petey with his move. So Bowser Jr. is your only option. He is fast, so run towards to Watermill, and the battle will start immediately without the cut scene. Don't doddle even after you beat him, as the timer is still ticking. You will win Power Star #3 (Unlike Super Mario Galaxy, you don't have to wait for Cosmic Stars to appear, they just appear right after you finish all the other missions).