One result of the rise of the oceans was an ecological wipeout. Perhaps the most striking – after, say, the melting ice caps and so on – was the decline of the redwood forests of northern California.
The ancient redwoods were huge, and the rising seas did not eclipse them. But the trees drowned in salt water, and the natural defense of the redwood – its toxic bark – became its means of revenge. Leaching from the dead trees, those toxins prevented the growth of any other life. Even the mighty sea could not overcome that, and so if you visit the forests now, you will find the Red Glades.
Picture a terrifying horror movie set, with dark water of unknowable depth, broken by skeletal trees of unknowable height, and utter silence expect for the slow lapping of the tides. Now imagine that it extends for hundreds of miles in all directions. And that there is absolutely nothing living there.
If you drink the water, you will die. If you swim in the water more than a few minutes without chemical protection, you will be sick and possibly die. If you try to climb out and a sodden, rotten branch breaks and you fall, you will die.