Looking at this picture, do you automatically assume it is a lake? No, it is neither a pond nor a lake.
This used to be a quarry. Rocks are blasted from these granite boulders for construction and other materials. Pulau Ubin have several sites with granite quarries. These quarries are no longer in operation. Over time, water fill up the concave land and this soon turn into a watery enclave that attracts wildlife and humans.
But beware, this is not a place for swimming. There have been several drowning incidents. Heed the warning sign – do not swim here!
Let nature be. Simply enjoy the scenery and move on.