Malaysia's first hill resort, Penang Hill is only 833m (2,723 ft.) above sea level, but it is noticeably cooler than the rest of the island. At the top, you will find the Kek Lok Si Temple and Thee Kong Tua (Temple of the Jade Emperor; Air Hitam; no phone; free admission; daily 9am-5pm), a Taoist temple dedicated to the supreme ruler of heaven. The hills are covered with jungle and 20 nature trails with great trekking.
Penang Hill was formerly reached by an old funicular railway that started from the base station at Air Hitam and traversed to the top of the hill. It's been closed for renovations that will remove all traces of the old railway and install new cars and track, but no official authorities have been able to give a clear estimate of when the new railway will be opened. When you visit, do contact the tourism board to find out if it's reopened, because it's a nice ride up the hill, even if the old wooden cars have been replaced. You can also trek up to the top of Penang Hill starting from the "Moon Gate" at the entrance to the Botanical Garden for a 5.5km (3 1/2-mile), 3-hour hike to the summit.