Sea Serpents

The littl'uns is not too much trouble a-tall. It's the mothers and fathers that are the worst.

d4	The first sign is ...
1	when really small ones (garter snake sized) turn up in nets or on hooks, and nip at sailors
2	mass migrations of fish, turtles, even sharks give the area a wide berth
3	the python-sized one coiled around the sounding line takes a careless sailor's hand
4	when a large one breaches, almost mast-high, with a roar and spray of water

d6	The predominant breed here seems to be...
1	mostly benign and herbivorous, munching morosely on kelp, they stare at you cautiously like cows. Taste delicious too
2	conventional plesiosaurus, but extremely territorial. Their teeth trade well with merfolk
3	eel-like and electrified, they fill the water with a powerful current to stun their prey. Pharyngeal jaws and eerie goat eyes
4	long-necked and snub-nosed with dozens of frenetic, flapping fins all along their body and twitching barbel-beards. They tend to hunt at night, and if disturbed during the day, cast Darkness
5	wood-hungry, with saw-like teeth, they grind at hulls like rasps. Their bodies are covered in a pale blue magic algae, that can be used as a poultice to cast Cure Wounds
6	related to dragons - they snake through the air without wings and speak in booming, haughty voices, demanding tribute be dumped into the drink, lest they send you sinking down to visit the sea goddess

d8	They seem to prefer this area to spawn because...
1	of its proximity to ample food sources and usually calm water
2	their ancient genetic homing instinct guides them here to rich and ruddy plankton blooms
3	undersea volcanoes manage to keep the water surprisingly warm
4	the frigid waters here help winnow their large clutches of young
5	powerful, undersea Ley Lines converge here
6	they are cultivated here - beneath the waves lies a great merfolk city
7	this was once a continent dominated by ophidians. An open dimensional portal to the plane of serpents still oozes green light below
8	a dead Sea Titan's corpse has provided food and shelter here for their young, stretching back millennia. An impossibly large sword hilt raises well above the waves and is covered in guano and squawking sea birds