The Crater of Ngorongoro , Tanzania, is the largest crater in the world. There is a lake in the middle of the crater.
Takeoff from Lake Manyara (HTLM). Climb to an altitude of at least 7500 ft and fly heading 305 for 14 nm. You will now have the crater just in front of you. Descent and fly down the crater. There is plenty of flat and open land in the crater to make a landing. Finally return to HTLM.