OK, First up: Hostus Mostus' realm.

The high level ocean encounter charts have magical islands as a possibility, but you're in a known (to the DM at least) area with no islands, so I turned to Tasha's which has an expansion of the Eberron 3.5 phenomena of thin spots between the Prime and other planes.

Hence an Alien Island becomes the closest (in character) Supernatural Region: The Far Realm.

Hostus was just a poor sailor that had one of each Symbiont Magic Item from Eberron RoLW. Well, two tentacles. The "Mostus" was a reference to just how many things were living off him: as many as possible.

The only Class that would allow waterbreathing was Warlock, which made sense anyhow. So I made him Chan=in pact for another symbiont, this one with some degree of freedom. Opened the DM to monster creation, set my goal at CR 6 (a workout of a party of 4  7th levels, but not too hazardous) and figured out his level by hits and known AC. Filled in Invocations by need for survival in water and symbiont, plus what sybionts might be able to do for him (False Life, for instance)

Filled out spells based on what the Symbionts already had, then got more of the same, plus a speed spell for chasing ships and Vampiric Touch (which he was about to use when he died) to help offset the symbionts' drain on him.

One of the symbionts turns his dead body into a black pudding, BTW.

And that gave you all a bit of experience for the Far Realm Region. 3 critter's worth. Now all you ahve to do is survive it.
This message was lightly edited by the GM at 20:01, Wed 08 Sept 2021.

This should probably go in the current IC thread, but it'll get lost in new messages.

The village has a dock big enough to hold a longship. The dock has two sides, of course, so that's 2 longships, tops.

The town has a couple of buildings, but only barely. A small Tavern for visiting sailors, 2 Longhouses: One for housing new colonists, one as a warehouse.

The butcher/leathersmith is in another, the blacksmith in another, and number 6 is the headman, the local Jarl. Both his business office and his home.

Oh, there will be cook fires outside the dorm, and possibly piles of lumber if new farmland is being cleared. A cooper is due any ship now, and maybe a wagon smith, if they get lucky.

This colony is still in it's first generation, but it's been around a few years.
This message had punctuation tweaked by the GM at 20:01, Wed 08 Sept 2021.

It was supposed to be 6 Giant spiders, but the players wanted more, and couldn't wait for Mexico, so...

I expanded it to a spider infested forest. I looked up all spider adjacent things and... Came up with 4 that worked.

&5 Giant spiders, able to spin webs and make the walls for the ever grown complex.. 25 giant wolf spiders. Smaller and not web spinners, but able to patrol the interior of the complex and harvest smaller critters that get stuck in the web.

But they needed a central brain. Spiders are not hive insects, after all. So..an ettercap. But a simple ettecap doesn't add challenge, so...make it a druid, that being appropriate for the uninhabited area. Well, that or sorcerer, but druid ahs certain animal (spider) control abilities.

Land Druid (forest). Domain spells are fixed and add some emergency coverage (and at least one is just useless). Chosen spells and cantrips: poison based or spider/animal based. No summons, as Ettercap hate Fey, and summons are fey. Still, animal control explains a lot for the situation, and a few others are handy. One gives Advantage on melee attacks, bring the garrote into play, for instance. And 2 ASIs actually made for a decent Int on the ettercap.

Of course, this limited spell selection for combat, but then, it was wasn't really a concern from the RP standpoint. 101 spiders as bodyguards should be fairly effective.

The spiders: Species 1 and 2 were merely standard Giant and Giant wolf spiders. Species 3 was normal tiny spiders under an Insect Growth spell. Species 4 was a wildshaped druid under a spell that also altered appearance a bit...which also explains 2 apparent species of ettercap.

So we have 100 spiders coming to see what the holy hell is causing all that web disturbance, and the boss and his pet super spider finally noticing and joining the fun.

All because you asked for it. Careful what you wish for.

Oh, there IS treasure, but it's limited by circumstance. it won't include coin or art objects, obviously.

The random ship generator in GoS calls for a wraith Captain, Wraith officers, and a crew of specters, zombies, and skeletons. But the numbers are strange.

Crew is 10% specter, 45% each zombie and skeleton. But there are 5 ship's officers as part of that crew. That would make for 6 wraith, each able to make and control 7 specters, for about 42 specters. The whole crew of a longship, basically (and all incorporeal, hence unable to actually do crew duties). Even just the 6 wraiths and 4 specters the random encounter table called for was a bit over the top.

So: one Wraith, as captain, his 7 specters as officers and etc, and about 18 each zombies and skeletons.

More reasonable as an encounter for a party without a cleric.

Then, just to be different, I made one of the specters a Poltergeist variant, which gives the ship something like Marvek's ability to boost speed by wind effect. But that was outside logical adjusting of the random encounter. That was just for me.

Oh, and they hide in the bilge during daylight. Time of encounter actually WAS random, just bad luck.