Trou Aux Cerfs is a dormant volcano with a crater lake in the center situated just outside the center of Curepipe. There is a road closed to traffic that goes around the rim with viewpoints down into the crater. It is one of the higher points on the island and provides panoramic views of the area.
Route:
The trail loop around the crater is .8 miles at roughly 2000ft of altitude. There are a few trails that begin descending towards the crater, but they seem to fade into thick trees/shrubs. There is likely a way down though as I did not explore them all.