If you want to get on the water on a board, try The Stand Up Paddle School at Tanjong Beach Club on Sentosa Island.(Apologies for mentioning the dirty word on this forum)
www.supschool.com.sg/. They have good quality boards at an amazing location with warm water and warm hospitality. Tanjong Beach is also hope to the Singapore Paddling Club who paddle Outrigger Canoes among other things and has a health contingent of expat Aussies and Kiwis. A great place to catch a beer with some locals. Isabelle who owns and runs the SUP school is awesome, and lived in Australia for a while. Not too far a walk from the Wavehouse.