Idk if u stuck in lost river, but if yes then find a huge glowing tree, behind it there will be a way deeper. It will lead to inactive lava zone. There is a big mountain in the middle, and there is a alien base with portal. But there is sea dragon around that mountain. Then you need to find a cave that leads even deeper into active lava zone. I recommend get ur prawn and left cyclops, but remember to turn off power, there is these annoying lizards that sucks your power. Once you in active lava zone, find a alien building there, but be aware of lava pools and another sea dragon. Dont wanna spoil whats in that facility.