Similar flavor as Initiate of the Deserts and Initiate of the Swamps for this missing aspect of nature.

1) Allows Entangle on and in water like a mariner via surrounding seaweed.
2) Increased power of Tsunami like other edges do for Whirling Simoon
3) Whatever else immortals think is cool? Water breathing? Primordial? Herbal medicine?

4) Lose ability to select Deserts or Swamps edges in line with what happens if you choose those edges.

Thanks, think this is a fun suggestion in place of the druid specialization that has been on the back burner for years :)