OK, warning, you've heard of flash floods, so don't enter if you see that Bukit Timah Canal is flooded, if it's been raining, or if it's about to rain. You shoes should be completely dry all the way. If they have to get wet, don't proceed! Use your turtle sense and come in only when it's safe.
Here's how to get in. At the entrance, make sure no one's looking before hopping over the fence and going down the ladder. Then, it's time to take out your torchlight (bring two, trust me) and follow the tunnel... It's pitch black, and claustrophobic, and silent, and spooky... but think back on your ninja training. You can do it! After a bit, the ceiling starts to get lower and lower, but keep going and you'll find that it soon opens up to a cavern with sky lights. Keep walking from here and you'll know when you've reached the cache when you reach a ladder. Next to it is an exit with rope attached for you to climb out. Where does it lead?! Hope you have fun with the adventure!
Slight risk - be careful of your back when bending over also; take it slow.
Torchlight needed (2 recommended)
Some rope climbing
You can check your answers for this puzzle on Geochecker.com.
November 2022
Cache is in good condition despite hanging there for 7 years! But original inhabitants of the sewer exit no longer live there.
To get to the entrance, first find the sewer from the path. Then take north tunnel (not South) about 100m until you find a ladder.
The coordinates appear be a bit off. If you have trouble finding, look for a parallel path and a point about 30m to the West.
And ok, the Terrain difficulty has been adjusted to 3.5. Careful climbing out!