I know this has been done to death but... In December last year I faltered with Aquaria within about 4 hours. This was mainly due to the inability to annotate the map in some way - even if just to place a marker that I know means "come back and investigate" or "this way is currently blocked". At the time it got all too hard, and coupled with moving house, living with the in-laws etc, I just gave up.
I'm playing again from the beginning and enjoying it, but can sense the same problem looming. I couldn't find anything concrete on the 1.1.0 patch, but is some kind of user-driven map annotation on the cards (no matter how simple it is) ?