Coastal Shelf

Coastal Shelf
Karim saari, CC BY 4.0, Wikimedia Commons

The shallow sea over the edge of a continent, green or grey rather than blue, where most fishing boats work. Its swell is short and choppy, its fogs come in without warning, and on deck everything smells of brine, tar and fish. Cod, herring, mackerel and flatfish crowd its banks, seals and porpoises follow them, and gulls follow the boats. Fishermen, traders and navies cross it every day, and its sandbanks, wrecks and lightships are known by name along the coast. People fear the sudden gale, the fog on the banks, and the shallows that break a keel far from any land in sight. The North Sea, shallow and stormy over its sandy banks, is a sea of this kind.

Hear it

For the table

Ground
At sea: Sailing ship: 77 km a day, Warship: 96 km a day, Galley: 154 km a day, Longship: 115 km a day, Dhow: 223 km a day, Junk: 223 km a day, Steamship: 444 km a day, Ironclad: 401 km a day, Ocean liner: 934 km a day, Cargo ship: 667 km a day, Sailing yacht: 266 km a day, Survey craft: 888 km a day, Submersible: 355 km a day
Water
by season
Foraging
rich

Hazards

  • Storm at sea. The wind rises for hours, the sea builds into grey hills and the crew reefs the sails or runs before it. No one sleeps dry; the ship goes where the storm sends it, not where the chart says.
  • Rain squall. A black wall of rain walks across the water and swallows the ship. For an hour the bow cannot be seen from the stern.
  • Sea fog. A white fog lies on the water. Bells and shouts carry strangely, another ship can loom up a cable away, and the coast is wherever the lead line says it is.
  • Reefs and shoals. Rock or coral a fathom under the surface, a sandbank that moved since the chart was drawn. A ship that strikes may float off at the next tide, or open her hull.
  • Becalmed. Not a breath of wind. The sails hang, the sea turns to oil, the sun beats on the deck and the water casks go down while the ship goes nowhere.
  • Man overboard. A green sea sweeps the deck, or a foot slips at the rail, and someone is in the water. By the time the ship comes about, the swimmer is a dot among the waves.
  • Fall from the rigging. Aloft in a blow, a frozen hand lets go of a wet line. Falling onto the deck breaks bones; falling into the sea is luckier, if someone sees it.
  • Seasickness. Landsmen turn green the first days out, or when the sea gets up. Most find their sea legs in two or three days; a few never do.
  • Frigid water. In cold seas a fall overboard is a race against the cold. The swimmer loses the use of hands, then of legs, long before drowning.

D&D 5e

Plays as
waterborne, by the ship pace at most
Checks
forage: Survival DC 15 · find the way: DC 10 · search: DC 15
Creatures are spotted at
6d6 × 10 ft
  • Storm at sea. Strong wind gives Disadvantage on ranged weapon attacks, puts out open flames and scatters fog; a flyer must land at the end of its turn or fall. A ship sailing into a strong wind moves at half speed.
  • Rain squall. Heavy rain makes everything in it Lightly Obscured, gives Disadvantage on all Wisdom (Perception) checks and puts out open flames.
  • Sea fog. Heavy fog is Heavily Obscured: a creature trying to see something in it has the Blinded condition. Patchy fog is Lightly Obscured: Disadvantage on Wisdom (Perception) checks that rely on sight.
  • Reefs and shoals. (House rule) House rule: the lookout makes a Wisdom (Perception) check, DC 15 by day, 20 at night or in rain. On a failure the ship strikes: it takes 4d10 Bludgeoning damage (reduced by its damage threshold as usual) and stops until the crew warps it off, about an hour of work per 10 damage taken.
  • Becalmed. In a dead calm a ship cannot move under sail: it must be rowed, or it lies still. A ship that cannot be rowed makes no way that day.
  • Man overboard. Swimming costs 1 extra foot of movement for each foot moved (none with a Swim Speed). In rough water the GM may ask a DC 15 Strength (Athletics) check to move at all.
  • Fall from the rigging. A fall deals 1d6 Bludgeoning damage per 3 m (10 ft), at most 20d6, and leaves the creature Prone unless it took no damage. Falling into water, it can use its Reaction for a DC 15 Strength (Athletics) or Dexterity (Acrobatics) check to enter head or feet first and halve the damage.
  • Seasickness. (House rule) House rule: a creature new to the sea makes a DC 10 Constitution save at the start of each of its first three days aboard, and on any storm day. On a failure it has the Poisoned condition until the next dawn. A success on two days in a row ends the risk for the voyage, except in storms.
  • Frigid water. A creature can stay in frigid water for as many minutes as its Constitution score. Each minute after that, it makes a DC 10 Constitution save or gains 1 Exhaustion level. Cold resistance or immunity, or being adapted to icy water, passes automatically.

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

Adventure hooks

  1. Fishermen have dragged up the upper half of a bronze statue in their net. Two scholars are bidding for it, and a third stranger offers more than both to have it dropped back exactly where it was found.
  2. The herring have left the old banks, and the fleets of two harbours are crowding onto the last good ground. A skipper wants a crew bold enough to fish in the other harbour’s waters, and a few fists.
  3. Fog has come down over the banks and the boats ring their bells to find each other. One of the bells answering belongs to a boat lost with all hands last winter.
  4. A fisherman found a gold ring in a cod and became the richest man in the harbour. Now every crew guts its cod at sea, and someone ashore is quietly selling rings to slip inside them.

What grows here

  • Eelgrass (grass). The most widespread seagrass of the northern hemisphere, with ribbon leaves up to over a metre long, growing on sand and mud below the low spring tides in bays, lagoons and estuaries of the North Atlantic and North Pacific, as far as Iceland and under months of Arctic ice. Its meadows shelter herring spawn and young cod and feed brant geese, and when it washes ashore it feeds a whole world of sand-hoppers, flies and beetles; a wasting disease in the 1930s killed much of it. It roofed houses on Læsø in Denmark, fed cattle in Norway and stuffed mattresses, and the Seri of Mexico toasted and ground its grains. Gives: Dried Eelgrass.
  • Enhalus (grass). A large seagrass of the tropical Indian and western Pacific Oceans, from the Red Sea and Mozambique to Papua New Guinea, with strap leaves 30 to 150 cm long on thick rhizomes anchored in mud, sand flats and coral ground, mostly just above the low spring-tide line and down to 4 m. Its leaves make up much of the shallow seagrass meadows, often mixed with Thalassia hemprichii, and give room to the small life that grows on them. It is the only seagrass pollinated at the surface: the male flowers break off and float until they reach a female flower, and the round fruit, 4 to 6 cm across, is drawn back under water to ripen.
  • Neptune Grass (grass). A seagrass found only in the Mediterranean, whose ribbon leaves up to about 1.5 m long form great meadows from 1 to 35 m deep in clear water; one clone off Ibiza and Formentera, 8 km across, may be 100,000 years old. It flowers in autumn and gives floating fruits in spring, the sea olives, and balls of its fibre, Neptune balls, wash up on the beaches with heaps of dead leaves. Its meadows break the waves and shelter much life. Its dried leaves once insulated roofs, bedded animals and packed fragile goods (in Italy, alga dei vetrai), and were used for inflammations and irritations. Gives: Dried Neptune Grass.
  • Turtle Grass (grass). A seagrass of the Caribbean and the Gulf of Mexico with ribbon leaves up to 30 cm long, rooted by rhizomes buried in the sand. It carpets calm, salty lagoons from the low-tide line down to about 30 m, on muddy sand, coarse sand and clay. Its meadows shelter young fish and feed turtles, parrotfish, surgeonfish and sea urchins; people use it only in the aquarium trade.
  • Irish Moss (seaweed). A small fan-shaped red seaweed, a little over 20 cm, green near the surface and deep red lower down, growing on rocks from mid-tide to the sea floor along European and Canadian Atlantic shores. Boiled in milk, strained and sweetened, it sets into carrageen pudding in Ireland, Scotland and Brittany; it also fines beer and goes into medicines. Its carrageenan thickens ice cream and milk products. Gives: Carrageen.
  • Ogo (seaweed). Gracilaria is a large genus of red seaweeds of warm seas, which cannot bear water below 10 °C and are most varied in the western Pacific. They are eaten across Asia and the Pacific: ogo in Hawaiian poke, gulaman jelly in the Philippines, and soup with coconut cream and lime in Sri Lanka; they are also eaten in Korea, and in Jamaica the weed is called Irish moss. Over 90% of the world's agar, a vegetable jelly, comes from them. On Guam, deaths followed meals of it, most likely from toxic blue-green algae growing on the weed. Gives: Ogo.
  • Sea Grapes (seaweed). A green seaweed of the coasts of Southeast Asia, Oceania and East Asia, up to 30 cm long, covered in tiny bubbles like a miniature bunch of grapes. The bubbles burst in the mouth with a taste of the sea. It is eaten raw, alone or in salads: lato in the Philippines, umibudo in Okinawa. Farmed in the Philippines since the 1950s, later in Japan, Vietnam, Taiwan and China. Gives: Sea Grapes.
  • Sea Lettuce (seaweed). A thin bright green seaweed found on coasts all over the world, fixed to rocks, jetties, shells and other algae from the upper shore down to about 10 m, and most abundant where the water is rich in nutrients. It is eaten raw or cooked: in soups and salads in Scotland, salted with raw fish or boiled as soup in Hawaii; it also serves as fertiliser. Piles of it rotting on the shore give off toxic hydrogen sulphide, as in Brittany in 2009. Gives: Sea Lettuce.
  • Wakame (seaweed). A kelp of the cold temperate coasts of Japan, Korea, China and Russia, long collected for food in East Asia and farmed in Japan since the 8th century; Brittany has farmed it since 1983. Carried on ships' hulls, it has taken hold from New Zealand and Australia to Argentina, California and Europe, and is listed among the hundred worst invasive species: it grows thick on any hard surface and outcompetes native plants and animals for light and space. It is eaten dried or salted in miso soup and salads, and in Korea as miyeok-guk soup, given to new mothers. Gives: Wakame.

Animals

Creatures

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

To gather

Bearded Seal Blubber, Bearded Seal Hide, Bearded Seal Meat, California Mussel, California Spiny Lobster Meat, Caribbean Spiny Lobster Meat, Periwinkles, Dried Eelgrass, Giant Pacific Octopus Meat, Humpback Whale Blubber, Humpback Whale Meat, Carrageen, Killer Whale Blubber, Killer Whale Meat, Loggerhead Turtle Meat, Narwhal Blubber, Narwhal Sinew, Narwhal Skin, Dried Neptune Grass, Northern Gannet Oil, Northern Gannet Feathers, Northern Gannet Chick, Ogo, Razor Clams, Ringed Seal Meat, Ringed Seal Oil, Ringed Seal Skin, Saltwater Crocodile Meat, Sea Grapes, Sea Lettuce, Sea Lion Hide, Sea Lion Meat, Sea Lion Oil, Wakame, Penguin Meat, Dugong Meat, Dugong Oil, Dugong Tusk, Calipee, Japanese Spider Crab Meat, Leatherback Turtle Oil, Polar Bear Fat, Conch Meat, Queen Conch Shell, Sea Urchin Roe, Saltwater Crocodile Hide, Trepang, Weddell Seal Blubber, Weddell Seal Meat, Tortoiseshell, Killer Whale Tympani, Slipper Lobster Meat, Narwhal Tusk, Polar Bear Hide, Sea Otter Pelt, Snake Venom, Concentrated Venom

Nearby biomes

Coral Reef, Kelp Forest, Open Ocean, Deep Sea

Open it in Biomes — MGS Toolbox