Underwater and Aquatic rules / 3pp / homebrew? 5e

[bookrat]

What kind of homebrew and 3pp underwater rules and guidelines are out there? What have you come up with in game?

Movement, sight, combat, anything.

The books are fairly limiting.

PHB:

When adventurers pursue sahuagin back to their undersea homes, fight off sharks in an ancient shipwreck, or find themselves in a flooded dungeon room, they must fight in a challenging environment. Underwater the following rules apply.

When making a melee weapon attack, a creature that doesn’t have a swimming speed (either natural or granted by magic) has disadvantage on the attack roll unless the weapon is a dagger, javelin, shortsword, spear, or trident.

A ranged weapon attack automatically misses a target beyond the weapon’s normal range. Even against a target within normal range, the attack roll has disadvantage unless the weapon is a crossbow, a net, or a weapon that is thrown like a javelin (including a spear, trident, or dart).

Creatures and objects that are fully immersed in water have resistance to fire damage.

DMG:

Unless aided by magic, a character can't swim for a full 8 hours per day. After each hour of swimming, a character must succeed on a DC 10 Constitution saving throw or gain one level of exhaustion.

A creature that has a swimming speed-including a character with a ring of swimming or similar magic can swim all day without penalty and uses the normal forced march rules in the Player's Handbook.

Swimming through deep water is similar to traveling at high altitudes, because of the water's pressure and cold temperature. For a creature without a swimming speed, each hour spent swimming at a depth greater than 100 feet counts as 2 hours for the purpose of determining exhaustion. Swimming for an hour at a depth greater than 200 feet counts as 4 hours.

UNDERWATER VISIBILITY
Visibility underwater depends on water clarity and the available light. Unless the characters have light sources, use the Underwater Encounter Distance table to determine the distance at which characters underwater become aware of a possible encounter.

UNDERWATER ENCOUNTER DISTANCE
Clear water, bright light: 60 ft
Clear water, dim light: 30 ft
Murky water or no light: 10 ft

[SmiloDan]

I think it's pretty basic for a reason. It's just easier to run that way.

The only other thing I can think of is maybe give submerged characters Resistance to non-natural Bludgeoning and Slashing damage?

What else are you looking for?

[Lorathorn]

I swear there was some Patreon for a writer that focused on 5e underwater rules. Like for underwater campaigns.

[bookrat]

I'm about to run and underwater dungeon (homebrew) for the OotA game. I was just looking to see what was out there and see what I wanted to adopt and add in. Like effects of heavy armor in deep water or swarms of fishes attacking them or what it's like to move.

I've never done underwater stuff before.