First you have to head over to the dojo courtyard via Map.
After the dojo courtyard and then into the Water Dojo.
To earn the whole Water Ninja Suit, You need to play Matches with other penguins. And earn points.Unlike Card-Jitsu Snow random players shall not join you.
So, To earn points you need to play Matches right? Do you know how to play? If you don't click on Sensei at the Dojo and he'll explain you how to play Card-Jitsu Water.
Choose a card from the bottom of your screen.
Empty stones by making the elements disappear. You may have to play several cards on the same stone.
Pick an empty, glowing stone to move. Remember – you can jump diagonally!
Reach the gong or be the last ninja standing to win! The further ahead you are, the more experience you’ll earn.
Kick the gong to earn bonus experience points.Add elements to stones in front of your opponents to slow them down.
You are ready to Batlle with sensei. Once you have collected all the Water Ninja Items, Challenge Sensei. It may take a while to win. But you'll win for sure. Card-Jitsu Water is all about Timing and Speed.
After you beat Sensei you'll earn the water gem. Wear the suit and the gem to perform special water-moves.
Congragulations!, You have finally become a Water Ninja.
Source: Club Penguin Wiki
