Help in the Face of Danger

So recently, I've gotten a new DM. This guy is somewhat serious, but will and is cracked down by a rules master we have working in the store. In addition, anything too wild is cracked down on, leaving some sense of realism cracked by the rules.
He has just declared that I will be going into a high seas adventure as a pirate. He has refused to provide any additional info. This is 5e D&D.

There is just one problem.
>This guy loves Cthulu mythos.
He throws tons of Cthulu monsters at his players, and they tend to be see and die. The hounds, everything. He has bunches of books for entries on monsters alone.

How do I counter this. How do I ensure survival. I know some of you guys fawn over the Cthulu mythos. I need you knowledge. I'm playing a ranger, beast master, human. Gold and stats will be rolled for.
What do I do? What do I get?
Save me.

The best suggestion would be getting a better GM. Either that, or since he likes Cthulhu, roll Old Man Henderson.

He knows Old Man Henderson.
So does the crack-down employee. That would fail immediately.
And I currently can not get a better GM. That is why I am asking for advice and knowledge in how to deal with the variety of monsters from the mythos.
(and for any additional posters, please don't forget we are pirates. that probably counts for something-like aquatic monsters being probs the biggest threat.)

And as a general pointer for any additional replies, shenanigans will most likely fail. So will screwing over the party actively.

So I need legitimate counters and knowledge of how certain creatures can be beat.

And what's wrong with this?

Seconding this question.

I never said it was wrong. I was, however, asking for advice. I have little to no knowledge of mythos, and knowing how the DMs operate (especially this one), that could get me killed repeatedly. Now that would become a problem, and this is my solution.

This better not be you, Mr.DM at a store that may or may not be named Ronin.

So, you don't make your character too involved and get ready to make a new one if you die, or leave the game if it turns out to not be your thing? Maybe read a bit of Lovecraft to get a feel for the style?

I still don't understand what you want help with.

Can't leave the game, and DMs force you to be heavily involved.
And I do want to be involved. Not much point playing a roleplaying game if your just a stat block.
I'm asking for advice on how to handle the monsters of mythos, which ones have no counters of mundane means, which ones do, what are said mundane counters, what to expect.

I'm asking for knowledge. Knowledge on the mythos monsters. With that, well knowledge is the greatest weapon.

Tell your GM he's a retard for putting see-and-die tentacles in a D&D game.

That's called metagaming, user. Either just roll with it as events occur, or bow out of the game.

Well, I don't know much about 5e, but I know a fair amount about the mythos. It kind of depends on your DM's specific tastes. If he likes it more pulpy than existential, you can probably fight them, albeit it will be tough. If it's the latter, than trying to avoid their attention is best. If that fails, kill their cultists(if they're a being that had a cult) around them. If you get true to mythos Hounds of Tindalos, you're fucked, unless you get to a pocket dimension with no acute angles.

Hounds of Tindalos are indeed there. And that whole area is what he prefers.

Per mythos, they travel throughout the 4th dimension of time and usually don't have much to do with the 3D world. Plus they can only enter this dimension via angles less than 120 degrees. Time travel is usually the only way to get their attention, but once you have it, they can literally just wait until you're 70 or something because time doesn't matter to them.

Shit.
Any other monsters like that?

Well, all of the Great Old Ones(Cthulhu, Yog-Sothoth, Nuib Shiggoroth). There's also the messenger of Azathoth, Nyarlothotep who had numerous "masks" or avatars that can have various powers/abilities depending on the specific mask. All the beings I just listed are effectively gods though, in terms of power.

There's Mi-Go, alien fungus creatures that like to put other creatures brains in metal tubes and do experiments. They can be destroyed by relatively "easy" but that's just in comparison to other things.

There's deep ones, which are fish/amphibian monster people, that can interbreed with other races. They too can be destroyed, and certain signs(possibly the Elder sign) can ward them off.

There's shuggoths, which are giant, amorphous blobs of muscle, mouths, and eyes. Depending on the interpretation, they can be killed... Albeit it would be damn hard and just better to run.

I'm expecting deep ones. The campaign is ocean-based. Anything noteworthy in there?

There's also Yithians, they do mind swaps to study shit and avoid extinction. They're, relatively, benign. There's also the Great Race, large intelligent plant-based species. Very hardy, may have created humanity for slave labor/entertainment/food

Shuggoths can also do fine in the water. Anyway, deep ones venerate two dieties(or just very old deep ones, they can only be killed via violence and I think they continue to grow throughout their very long lifespans) Father Dagon and Mother Hydra. They may be able to control other aquatic life.

It's also, in theory, possible to bargain with deep ones. As long as you don't mind impregnating/being impregnated by fish people.

You noted they can be warded off. Is there anything about those signs that is significant? If I saw one ingame, would I recognize it?
Is there also any general weakness? Some anons be calling me a metagamer, but I'm favoring the mythos as my enemy on the ranger. Taking no chances.
My DM better not magical realm this....

How old are you, OP?

Have you heard of this fancy new thing called weekeepeedja? Or goo-gel? I hear within their vast libraries they contain all knowledge.

19.
Small problem-vast

Hit Cthulhu with the boat.
That worked in the story.

I'm actually anticipating that.

Unless a kraken ties us down.

Look up the elder sign, there's a couple interpretations of what exactly it is. I prefer the one drawn by Lovecraft, but the one done by Derleth is more popular.

>pic related is Lovecraft's

Here's Derleth's.

Gotcha. Thanks a lot for all of this by the way.
Any other info I should be aware of? Mundane counters, oceanic creatures, mythos info?

>there is an actual employee at the store who monitors how people play pretend and enforces rules and """"" realism"""""

Literally what? Where the fuck is this shithole?