The summit of Kelimutu (1620m) forms a barren lunar landscape with, to the east, two vast turquoise pools separated by a narrow ridge. A few hundred metres to the west, settled in a deep depression, lies a dark khaki lake. The lakes’ colours are due partly to the levels of certain minerals that dissolve in them. As the sulphurous waters erode the caldera they lie in, they uncover bands of different compounds and, as the levels of these compounds are in constant flux, so are the colours. Just as important, however, is the level of oxygen dissolved in the water. When their supply is low, the lakes look green. Conversely, when they are rich in oxygen, they range from deep red to black. In the 1960s, the lakes were red, white and blue.

Every morning at around 4am tourists ride by ojek  from their hotel in Moni to Kelimutu, making it to the top in time to see the sun rise hazily over the mountains; make sure you organize this early departure the night before, though you can also go later if you prefer. Just before the car park near the summit you need to pay a park fee. There are two vantage points – you can only see two lakes from the first one, so most tourists and all the local coffee-sellers head to the second. The walk back down to Moni, which takes about two and a half hours, is a joy, especially in fine weather, providing views over rolling hills down to the sea. There’s a path to the right at the two white pillars around the 6km mark, which cuts a good 4km off the road route, taking you through some charming local villages and past the waterfall (air terjun) on the edge of Moni – a great spot for a dip. If you take this route you’ll need good shoes, as it gets very narrow and steep. Following the road, you’ll pass some hot springs in which to soak your tired feet. Be sure to take plenty of water, as even going downhill you’ll warm up quickly.