I'm not sure about the charges but i guess should be free.
Saw a photo book on chek jawa in the National Library before, lots
of very beautiful coral reefs, fishes and colourful crabs, lobsters
and shrimps there. I've been wanting to go for very long liao but
it seems that the tours are always fully booked, at least that's
what the NParks website always says whenever i go check.
But again i suppose restricting entry to check jawa is necessary
lah, or else people will start going there to steal the marine life
and make a big fortune selling the fishes.