Quoting D&D beyond > https://www.dndbeyond.com/classes/wa...urkerintheDeep

"You made a pact with an entity that lurks somewhere deep in the ocean, or even on the Elemental Plane of Water, such as a mighty kraken, an ancient primordial, or a monstrous being from creation’s earliest days. You serve as this creature’s eyes and ears, watching the world beyond its domain and reporting your findings. You may have gained this pact as a member of a cult dedicated to the entity or after your patron saved your life when you nearly drowned at sea."
I would suggest the following.
Alignment Restriction - Must be chaotic
Eldritch Blast Pact Damage - Cold (blue)
Pact Damage Save - Fortitude
1st-level pact Spell - Freezing Bolt
2st-level pact Spell - Knock
3st level pact spell - Frost Lance
4st level pact spell - Black Tentacles
5st pact spell - Cone of Cold
6st pact spell - Horrid Wilting or Polar ray
First Special Ability - Fathomless Soul - Watherbreathing + increased swiming speed
Guardian Grasp - Mobile tentacle that works like an summoned monster, with mobility