How does the speaker describe the sea as a final resting place? How does this develop the meaning of the poem?

The speaker describes the sea as though tempestous and uncalm at the surface, is very calm and silent deep in the bottom. It is so calm that the spirits have their meetings there and even the dead are found there. "The awful spirits of the deep hold their communion there; And there are those for whom we weep, The young, the bright, the fair.