They are full-blood Jotnar, for starters. Ran dragged sailors down to her hall in nets. Her nine daughters, ocean waves all, may have been the mothers of Heimdallr. Water can transport. Water can yield riches.
Water can kill.
Folks in danger of drowning kept a bit of gold for Ran on themselves. A pile of gold lights her undersea hall in lieu of fire. Once there, though, they were feasted royally. Interestingly, intuitive cooks who can come up, on the spot, with delicious dishes made with whatever's on hand without resorting to recipes can as a rule deal safely with Ran and Aegir. Remember their big cauldron, which forms one of several ties between Perthro and Laguz.