Despite being an island nation, Singapore does not have too much in the way of beaches. One area I visited to take in the sun and sand was East Coast Park.
Sri Senpaga Vinayagar Temple - if you are looking for a distinct Hindu Temple in an otherwise relatively quiet residential area, check this one out.
Pulau Ubin is an island off the north east of Singapore. It's a fifteen minute boat ride from Singapore. Once you are on the island you can rent a bike and ride through nature.