The Outer Ocean, Inner Ocean and Sea of Ghanuu go down to 2 miles deep in a few places. Mostly they are zero to 4,500 feet deep. Some shoals are mapped, others are not. Shoals are shallow areas that vary in depth. Some places a rowboat would have a tough passage, others have enough water over them to float small ships. Tides will affect this…
The Mountains of Death go as high as 20,000 feet. Rumors of heights of 30,000 feet have never been checked on.
The lakes on this continent are from 100 to 500 feet deep. A few are much deeper. Rumor has it that some lakes and ponds, within city walls, connect to the vast depths where the Dark Elves reside.
The Invisible River is mostly dry river bed. Some of the dry areas have water below the surface, some areas have no water below just a dry river bed. The deepest parts of the Invisible River are about 200 feet deep. The average river depth is 10 feet. This river has been known to drown unwary travelers by somehow diverting its waters.
The terrain on Crestar shows some action by glaciers, while land nearby to the glaciation doesn’t. The inhabitants don’t realize this is impossible, as Crestar is all they know.
The nations west of the Mountains of Death have few natural defenses, so any invasions via sea or land is a problem for them.
Most inhabited islands can survive with small populations hunting nothing but fish and growing a few food stuffs. The smaller islands must trade with others to survive. Larger islands have enough acerage they can maintain large populations with large crop yields, with fishing as a suppliment food during times of drought.