Deep Tideland
Where land and sea make battle, the turbulent forces of water against rock carves abyssal tunnels through the ground. The tunnels bore up into the sandy coast, forming swathes of beaches with giant tidal pools. The pools found in deep tidelands can extend well beyond the extent of light's penetration. Warm waters and colorful creatures dwell in the surface waters. These bely the true nature of the pools, which hide many dangers in their cruel depths.
Treasures of the sea congregate in deep tidelands. Ocean water is sifted through the filtering pools, and anything the tide brings in is collected in natural reservoirs. Crafty deepdwellers idle by these caches, aware that the bounty lures in reckless adventurers.
See pages 116 and 117 of the Dungeon Master's Guide for basic rules regarding underwater environments. See pages 202–207 of Ghosts of Saltmarsh for more in depth rules.
Tidal Pool Characteristics
Each pool in an area of deep tidelands is distinct. Slight differences in formative forces can result in wildly varying pools. You can use the tables in this section to determine the specific dimensions and characteristics of a deep tideland tidal pool.
Pool Density. A 1 mile strip of deep tideland contains 1d10 × 30 tidal pools.
Tidal Pool Depth
| 1d3 | Depth |
|---|---|
| 1 | The pool is shallow. It is 1d8 × 10 ft. deep at its deepest point. |
| 2 | The pool is deep. It is 2d6 × 50 ft. deep at its deepest point. |
| 3 | The pool is abyssal. It is 3d4 × 200 ft. deep at its deepest point. |
Tidal Pool Diameter
| 1d3 | Diameter |
|---|---|
| 1 | The pool is narrow. It is 1d4 × 5 ft. across. |
| 2 | The pool is wide. It is 2d4 × 10 ft. across. |
| 3 | The pool is gaping. It is 4d4 × 20 ft. across. |
Tidal Pool Turbulence
| 1d4 | Turbulence |
|---|---|
| 1 | The pool is calm. It has no current, and the water is clear. |
| 2 | The pool sloshes lightly. It has a slight current, and its area is lightly obscured. |
| 3 | The pool churns roughly. It has a moderate current, its area is difficult terrain, and the water is lightly obscured. |
| 4 | The pool rages with the might of the ocean. It has a strong current, its area is difficult terrain, and the water is heavily obscured. |
Hazards
This section describes some hazards that adventurers might encounter while exploring the pools in deep tidelands.
Brine Harpoons
In salty depths, regions of brine can rapidly crystallize. The base of a brine harpoon covers a 5-foot square. If a creature or object weighing 1 or more pounds comes into contact with the base, it instantly forms a spear 2d4 × 10 feet long. A creature can avoid the spear by making a DC 10 Dexterity saving throw. On a failed save, the brine harpoon deals 1d10 piercing damage and 1d10 necrotic damage.
Impostor Clams
Impostor clams are acidic blobs related to green slimes that disguise themselves as giant clams, hoping to dissolve anyone looking for precious pearls. A creature that comes into contact with an impostor clam is grappled (escape DC 13) and takes 1d10 acid damage at the start of each of their turns until they are freed. An effect that reveals shapechangers betrays the impostor clam's true nature.
Jets
Water jets gush with inpouring sea water. An object or creature that comes within 5 feet of a jet must succeed on a DC 13 Strength saving throw or be pushed 1d6 × 5 feet directly away from the jet.
Random Tidal Encounters
When exploring the depths, you can use the Random Tidal Encounters table to quickly generate combat ideas. The encounters presented in this section are meant to provide you with inspiration for formulating your own encounters on the fly. Use your power of improvisation to provide your players with a challenge that is fitting for their level.
Random Tidal Encounters
| 2d4 | Encounter |
|---|---|
| 2 | Blind giant |
| 3 | Fish eat fish |
| 4 | Garish critter |
| 5 | Glint |
| 6 | Residence |
| 7 | Surge |
| 8 | Trapped treasure |
Blind Giant. A massive, blind creature floats hauntingly through the depths. Its blindness gives the characters a chance to escape or hide before they're noticed.
Fish Eat Fish. The party encounters a creature of trivial difficulty. On the second round of combat, a much larger creature devours the first before attacking the party.
Garish Critter. A creature or a group of creatures from the deep lash out at the party. They're garishly decorated, with colorful scales, coralline horns, lavish jewels, or something else that makes sense for the given creature.
Glint. Characters with a passive perception of 15 or higher notice a glint in the distance. There is a 50% chance the glint is treasure and a 50% chance the glint shone from the scale of a hungry creature.
Residence. The characters encounter a residence. It can be natural, such as a cave, or a construction. Its inhabitant dwells within.
Surge. The water in the tidal pool suddenly surges. Creatures in the water must succeed on a DC 15 Strength saving throw or be battered against the terrain. There is a 50% chance that a hostile creature from the ocean is swept in with the surge.
Trapped Treasure. The characters come across trapped sunken treasure. The trappers intend to ensnare and drown victims for an easy meal.
Tidal Loot
When you roll for loot in a tide pool, you can roll on one of the tables in chapter 7 of the Dungeon Master's Guide, or you can roll on the Tidal Loot table below.
Tidal Loot
| d8 | Loot |
|---|---|
| 1 | pearl (100 gp) |
| 2 | brooch (25 gp) |
| 3 | fine wine (10 gp) |
| 4 | logbook |
| d8 | Loot |
|---|---|
| 5 | azurite (10 gp) |
| 6 | golden tooth (5 gp) |
| 7 | aquamarine (250 gp) |
| 8 | treasure map |
Treasure Map
Scroll, rarity varies
A treasure map is designed to lead its reader to great riches. The map is a furled scroll and is blank until it is used.
As an action, you can unfurl the map and spark its magic. Ghostly ink scribes itself on the scroll, crudely mapping a rectangular area of the terrain around you that is 10 miles by 5 miles and centered on yourself. A red X appears on the map over the location of the nearest magic item that is the same rarity as the treasure map and is neither being carried nor is attuned to a creature. If no such magic item exists within the area of the map, the X appears over the location of the nearest magic item of any rarity, and if no magic items are within the area, no X appears. The ink is permanent and the treasure map can be used only once.
Credit
- Created by Ogskive
- Made using GMBinder
- Scene by Mark Hobson
- Watercolor stain by Jared Ondricek