I was born in Iligan City. What I remember the most from my childhood is going to this place just on the outskirts of the city where they have outdoor swimming pools. There are probably about 20 of them (just an estimate) and the water is so clean because it comes from a waterfalls nearby. There are a few filters set up before the water reaches the pools. The water is also never stagnant. It beats any rec centre pool! I had my first swimming lessons here and clearly it was futile. Anyway, I am definitely checking that place out again when I visit.

http://en.wikipedia.org/wiki/Timoga_Spring_Pools