[Sailor Steve]

I have a huge mod list that seems to change every time I reinstall the game (which is every year or two), because after fourteen years people are still creating new mods for SH3.

Unfortunately I consider everything I use to be essential, so I'm always working on it. That said, you asked for a few most important mods, so here are the ones I consider absolutely vital:

GWX 3.0
Hardcode Fixes - h.sie
New Interiors 2.1D - FlakMonkey (I plan on trying the U-Boats Combination Mod as I hear it's a great improvement)
Assisted Plotting Mod - Observer
Waterstream+Exhaust Kombimod v2.3 - Rubini/Racerboy/h.sie
Das Boot Sound Mod SH3 - Sailor Steve, based on 'Projeckt Schwertfisch', by the SH2 modders
DBSM SH3 Speech Fix - Sailor Steve
Halo Not Visible Through Body - Anvart
Head 04 Fix - Anvart
No Continuous 'Ship Spotted'
Seabed Repair Mod - Mikhayl
Merchant Fleet Mod - Iambecomelife

I'm not sure what you mean about the "bottom mod". I always list them in proper order starting at the top and working down.

If you like I will gladly post my full mods list. Also a few years back I chronicled one of my massive start-overs on a day-by-day basis, with every failure and restart, including all the testing and all the help I received during that trial. I've become one of those who has as much fun fiddling with the game as I do playing it. I've learned a lot along the way, the biggest thing I've learned being how much knowledge I still lack. I'll never be a programmer and I'll never be a true modder, but I do like making the game feel more realistic for me. I'll post a link to that thread if you like, but I'll warn you in advance that there's a lot there, and not all of it is pretty.