crocodile not in macritchie. but relative large water monitor lizard. macritchie is a nice nice place to paddle. the air is good, the water is clean. most likely if you are there to try out recreational kayaking, you wont venture out into those lanes where the school and national sprint kayak and sprint canoe athletes are training.
check this webpage out from Singapore Canoe Federation
http://www.scf.org.sg/Facilities/PLDetails.htmlcheck out also the water sports community forum for water sports related infos.
www.hydrotribe.com