Ahhh found it finally SW ocean, very heavy.

It's actually all along the underwater borders of the map (and sometimes further in); anywhere you can find those faceted glowing crystal pillars, there will be the nodes you can mine for ambergris and element shards scattered somewhere around the base of that pillar.

There's some just west of Atlantis, for instance, as well as some between the wyvern volcano island and the main island's shoreline.

(If you fly along above the water, you can usually see the crystal pillars glowing underneath the surface, and know that heading underwater there can net you ambergris and element shards.)

There is a ton of it under water by aberration Island, look for the big green crystals. It will be at the base of it