IIRC the mats for the biggest depth module were in the inactive lava zone. I built a little base by the tree as a staging ground before heading deeper, but got the mats I needed on the first voyage and only stopped back in a few more times when passing by, mostly because I also set up a little farm there and also because it was just so beautiful there, hanging over a dark void surrounded by all the glowing plants and fish.
yeah it wasnt the depth i had issues with, it was literally fitting my submarine down there. my entrance to that entire subterranean area was too narrow for the sub. but yeah, i also made my base near the tree, i never really felt the need to build any deeper than that. excursions staged from there seemed to do just fine.
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IIRC the mats for the biggest depth module were in the inactive lava zone. I built a little base by the tree as a staging ground before heading deeper, but got the mats I needed on the first voyage and only stopped back in a few more times when passing by, mostly because I also set up a little farm there and also because it was just so beautiful there, hanging over a dark void surrounded by all the glowing plants and fish.
spoiler
yeah it wasnt the depth i had issues with, it was literally fitting my submarine down there. my entrance to that entire subterranean area was too narrow for the sub. but yeah, i also made my base near the tree, i never really felt the need to build any deeper than that. excursions staged from there seemed to do just fine.
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There is an entrance large enough for the sub in the north between the bulb zone and mountains.
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IIRC there are three entrances to the river and two are large enough to get the sub through, though one of those is a tight fit.