be more specific ;p

lvl 10 - Dunes parties
lvl 15 - Koroloka Tunnel
lvl 20 - Qufim parties
lvl 25 - Jungle parties
lvl 32 - Citadel parties
lvl 36 - Crawler's nest / Gustav Tunnel / Altep desert
lvl 40 - Secret room in Crawler's OR Quicksand Caves
lvl 50 - uh this is the weird level... Quicksand caves...
then there's plenty of places to go, including bibki bay, boyahda tree, Ullegrand Range, Castle Baileys, Under the prison in the Sandy Castle, Kuftal Tunnel, Cape Terrigan, Valley of sorrows, take your pick ;p

PT for mission: 2-3 (Dragon) and pretty much all the missions after that.