2 days is all you need here. The underwater world aquarium is best in the world. I got to touch the skin of manta rays. I went through a water tunned with sharks, eagle rays, manta's and huge fish swimming on top. I saw the biggest fish in the world. The most amazing creatures I have ever seen and never seen in my life. The asian water world is some of the most spectacular life. I saw a seahorses, the largest japanese crab, sponges, a variety of large turtles. I couldn't get enough.
The night safari. Saw my first hippopatomus, long nose indian crocodile, the largest bats in the world, the most beautiful lion...just like the one in Lion King, huge tiger and leopard.
Orchids....saw the most unique in the world.
It seems Singapore prides themselves on having some the worlds greatest things. Although, it is great I would have a difficult time following the rules. I was so tempted to jaywalk, eat and drink on the underground, and use napkins. I'm not sure how Singaporians wipe their hands... not even the eateries carry them.