Help? [Spoilers]

I have reached the lost river and built a base with a consistent power source. Now i just want to know, what to do next? I haven't looked at much spoilers and i don't know where to go. All help is appreciated.

EDIT: i want to say just in case, i don't want any major spoilers. Smaller spoilers are ok, like locations to alien bases, but major story elements are things i want to discover mainly myself.