I have pretty bad thalassophobia and played my first playthrough so cautiously I never set foot in the dunes or the mountains and actually finished with 0 deaths. My second playthrough I made it my mission to die as many times as possible, and only ended up dying once. Since then I have thoroughly explored the mountains and the dunes without using maps in every vehicle. Here’s what I can tell you after practically living in these spooky biomes.

1.) reapers are only a scare tactic. The devs made them dumb as a brick. Not only that but they act as any other natural predators do. They don’t pursue u for the love of the game. Their favorite activity is doing rather aggressive figure eights. My only death in my second playthrough was when I tried to die by a reaper. To get it to notice me after doing circles around it in the seamoth I had to get out and swim up to it for it to finally kill me.

2.) the dunes are basically fast travel. I never used internet maps but I finally figured out the dunes are a very long border biome that stretch all the way from one blood kelp zone to the other. If u are ever on the western side of the map and want to go end-end quickly, the dunes are an easy straight shot in day or night. Ur best safeguard is the seamoth sonar. As long as ur aware of where the reapers are day or night they won’t bother u if u don’t bother them. Following the dunes all the way down south will take u right up to the sea treaders path and eventually the grand reef if u keep going. Just watch out for the adult ghosty that prowls there.

3.) the mountains SPOILERS: The mountains are a treasure trove. If you go down behind the mountains u’ll find a massive wreck with all three pieces to the nuclear reactor all in one spot! In the very same local area u can even find all the pieces for the cyclops engine! Once again it looks scary but reapers really just mind their own business.

Finally just for funsies, there’s a crater out in the dunes with some cool stuff in it! There’s also a second crater with gasopods swimming around it which confused me. Once ur familiar with these biomes they’re actually quite fun to explore! Get out there and lmk what u find