DiveIn

Adds diving and swimming for players and configured creatures.

Normally mobs can't follow you underwater. So players with diving mod players can just attack mobs from above or below without getting hit. This mod changes that.
Also added a diving mechanic for players with configurable stamina drain according to depth

Configured mobs can attack you! No more hiding under their bellies.

Idle mobs would swim within the configured range

Recommend to use with RtDOcean. There is configured sample for it.

Player Diving

• Unlike vanilla Valheim, stamina regeneration while swimming can be enabled separately for surface swimming and midwater diving.
• Extra stamina drain scales linearly per meter of current liquid depth and stacks multiplicatively with run-swimming.
• Pressing the vanilla run key in water toggles Fast Swim, doubling overall swim speed by default and consuming configurable extra stamina. Swim skill still improves base swim speed by a configurable amount.
• Swimming key hint labels are localized for supported Valheim languages.
• Surface swimming keeps the player's vanilla swim depth and only changes depth while diving.
• Attacking, secondary attacking, and guarding underwater stop swim movement so combat input takes priority.
• Use equipment in water except that is in blacklist.

Creature Diving

• Configured monster prefabs stop avoiding water and can navigate underwater.
• Idle monsters use passive depth profiles and slowly drift within their assigned depth range.
• Alerted or chasing monsters adjust depth toward their target within global depth limits.
• Underwater pathing uses route checks and steering avoidance samples instead of blindly forcing success.
• Underwater creature movement uses high-quality move-plan checks by default.

DiveIn.yaml

This file defines which monsters can dive and what passive depth band each monster uses.

# Monster dive configuration for DiveIn.
# Unknown keys and duplicate keys are treated as errors and keep the previous applied settings.

surface_patrol: # You can use any group name. Add your own groups
  passive_min_depth: 0 # Shallowest passive dive depth used while the monster has no target and is not alerted.
  passive_center_depth: 10 # Center depth used by the passive sine-wave swimming pattern.
  passive_max_depth: 20 # Deepest passive dive depth used while the monster has no target and is not alerted.
  active_depth_adjust_speed: 2 # How quickly this group adjusts swim depth while alerted or chasing a target.
  prefabs: # Monster prefab names assigned to this passive profile group.
    - Leech
    - Abomination
    - Serpent
    - BonemawSerpent

mid_water:
  passive_min_depth: 0
  passive_center_depth: 15
  passive_max_depth: 30
  active_depth_adjust_speed: 2
  prefabs: []

deep_patrol:
  passive_min_depth: 10
  passive_center_depth: 20
  passive_max_depth: 30
  active_depth_adjust_speed: 2
  prefabs: []

## Mod prefabs sample

mods_surface:
  passive_min_depth: 0
  passive_center_depth: 10
  passive_max_depth: 20
  active_depth_adjust_speed: 2
  prefabs:
    - Neck_RtD
    - Animal_Dolphin_RtD
    - Animal_Cod_RtD
    ...

Notes:

• If the same prefab appears in multiple groups, only the first assignment is kept.
• Invalid YAML keeps the previously applied settings.
• When the server is the source of truth, clients use the synced server YAML instead of their local file.

Config

[1 - General]

## If on, the configuration is locked and can be changed by server admins only. [Synced with Server]
# Setting type: Toggle
# Default value: On
# Acceptable values: Off, On
Lock Configuration = On

[2a - Player Diving]

## Comma-separated item prefab names that remain restricted in water. Everything not listed is allowed in water by default. Example: BowFineWood,ShieldBronzeBuckler. [Synced with Server]
# Setting type: String
# Default value:
Water Equipment Blacklist =

## Multiplier applied to vanilla stamina regeneration while swimming on the surface with your head above water. 0 matches vanilla swimming behavior, 1 matches normal non-swimming stamina regeneration timing and rate. [Synced with Server]
# Setting type: Single
# Default value: 0.5
# Acceptable value range: From 0 to 1
Surface Stamina Regen Rate = 0.5

## Multiplier applied to vanilla stamina regeneration while your head is underwater. 0 makes stamina recover only after surfacing. [Synced with Server]
# Setting type: Single
# Default value: 0
# Acceptable value range: From 0 to 1
Midwater Stamina Regen Rate = 0

## Additional moving swim stamina drain percent per meter of current liquid depth. 1 means 30% extra at 30m; 2.5 means 75% extra at 30m. Applied multiplicatively with run-swimming stamina drain. [Synced with Server]
# Setting type: Single
# Default value: 2.5
# Acceptable value range: From 0 to 5
Water Depth Stamina Drain Multiplier = 2.5

## Base swim speed multiplier at Swim skill 100. 1.5 means +50%. [Synced with Server]
# Setting type: Single
# Default value: 1.5
# Acceptable value range: From 1 to 3
Swim Skill Speed Multiplier = 1.5

## Swim speed multiplier while Fast Swim is toggled on with the vanilla run key. Swim skill separately increases base swim speed. [Synced with Server]
# Setting type: Single
# Default value: 2
# Acceptable value range: From 1 to 3
Swim Run Speed Multiplier = 2

## Moving swim stamina drain multiplier while Fast Swim is toggled on. Applied multiplicatively with water depth stamina drain. [Synced with Server]
# Setting type: Single
# Default value: 2
# Acceptable value range: From 1 to 5
Swim Run Stamina Drain Multiplier = 2

[3 - Underwater Visuals]

## Whether underwater fog and reversed water surface styling are applied while submerged. [Not Synced with Server]
# Setting type: Toggle
# Default value: On
# Acceptable values: Off, On
Enable Underwater Visual Styling = On

## Underwater darkness added per meter of swim depth. 1 means 1% per meter, so 30m gives 30%. [Not Synced with Server]
# Setting type: Single
# Default value: 2
# Acceptable value range: From 0 to 10
Darkness Factor = 2

## Underwater fog density added per meter of swim depth. 1 means 1% per meter, so 30m adds 30%. [Not Synced with Server]
# Setting type: Single
# Default value: 1
# Acceptable value range: From 0 to 10
Murkiness Factor = 1

Git

The player diving implementation includes code derived and modified from UnderTheSea
https://github.com/searica/UnderTheSea
https://github.com/sighsorry1029/DiveIn