Subnautica scared the absolute goddamn bejesus out of me.

[air_show]

Oh, I finally got back to the game and got down into the lava hole again with my newly thermal upgraded sub and purple tablet in hand... only to discover it doesn’t work on the door I though I had to get into. From my he color of the recieved it looks like I need a blue tablet?

it appears I’ve missed something and am stuck not knowing what to do next.

 

[Purple]

Spoiler town go!

There are two major points of interest in Lethal Lava Land:
1- The alien containment facility which I assume you have just found. It has a... big front lawn and a guard dog of sorts, accessed from like this little ring in the ground of the main lava area floor and then you go through a quick little crack. To save you some backtracking in addition to a blue tablet you need another further in so maybe craft that first.
2- The power plant, AKA "the lava castle" which is... kinda hard to miss once you know what people call it. It's in the same general area as the floor ring access point to the location noted above, just kinda keep exploring around there until you find a very obvious landmark and probably another guard dog of sorts. Actually getting inside is a pain but you just kinda poke around towards the top and there's a sort of obvious entry point and you get in towards the middle, anyway, there's a blue tablet in there.

And then you're basically done, honestly. Bring snacks and drinks because both those areas can take a while to explore. Oh and if you want to avoid another potential huge source of frustration there's kind of a leap of faith into a big indoor pool in the one area. There's a teleporter out from there but it takes you WAY out, if you want to go back the way you came because you like, parked your cyclops at the front door with all your endgame stuff in the lockers, it's doable but it's a royal pain and you need to get tricky with the prawn's grappling hook or I think a seaglide assisted jump out of the water.

 

[Troa11]

And then you're basically done, honestly. Bring snacks and drinks because both those areas can take a while to explore. Oh and if you want to avoid another potential huge source of frustration there's kind of a leap of faith into a big indoor pool in the one area. There's a teleporter out from there but it takes you WAY out, if you want to go back the way you came because you like, parked your cyclops at the front door with all your endgame stuff in the lockers, it's doable but it's a royal pain and you need to get tricky with the prawn's grappling hook or I think a seaglide assisted jump out of the water.

I'm not opening up the game to verify, but if memory serves there is another portal in the same pool, a little more off the beaten path on the other side that simply takes you up and out of the pool. I can't remember if there's enough ion cubes in the pool to power both portals (I think there is) but this should not be an issue if you find it.

 

[air_show]

Haven’t read the spoilers yet but it sounds like exploring the area will get me what I need eventually. Also oh my god the typos in my last post. Made it real quick before bed and didn’t double check all my sloppy thumb typing.