The closest thing Singapore has for a "tropical island paradise" vibe is the 2 kilometer stretch of artificial beach in Sentosa island. The beach is divided into three: Siloso, Palawan and Tanjong. The second was supposedly named after the island in the Philippines where the white sand were taken from, and it is accessible using suspension bridge from Siloso. It's claim to fame is being somewhat dubiously the "most southernmost part of continental Asia."
Having been to several natural beaches I almost have the impression that the place is trying too hard to look pretty. There's the requisite groves of coconut trees, beach umbrellas and recliners abound, and of course, the implanted white sand. Several bars and restaurants line the beachfront, offering $9 beers and typical fares such as fish & chips. Most of the patrons were the locals who need a place to show off their Rip Curl boardies and some expats with their kids.
There are also several activities to be had around the beach: I enjoyed the Flowrider last year, there's the Songs of the Sea show, and there's a zipline and parachute ride simulator nearby. There are also theme parks such as the Universal Studios and Resorts World Singapore in the island, among others.
How to Get There: The beaches of Sentosa can be reach through the Sentosa Express monorail that plies from Harbour Front in the mainland to Beach station. Fare is SG$3, and includes entrance fees to the island.