This is a great escape from the bustle of the city just 12km away. Bukit Timah is a 160-hectare nature reserve that includes Singapore's highest hill (not very high at only 163.63m) and has the only substantial area of rainforest left in Singapore. We took a cab out and a bus back, but either way, it's easy, as there are several buses leaving Orchard Road for upper Bukit Timah Road and then it's a 10min walk to the reserve. A single hectare of this reserve contains more tree varieties than are in the entire of North America, so as you can imagine, the flora is great. The walks are colour coded and easy to find, but most start with a very steep climb on a tarmac path. After the climb, the going is fairly easy and very pleasant. The locals use the area for jogging and walking and are in abundance in the early morning. Animal life includes long-tailed macaque, geckos, flying lemur, anteaters, tree snakes, pythons and hundreds of birds of varying colours. The sounds are amazing, though you are lucky to spot anything amongst the trees.
In summary, a welcome break from the city and easy to reach if you make the effort.