How are the land area and the oceans affected during the ice age?

During a glaciation:

Sea-level falls (world-wide - the phrase "rising sea-levels", in the plural, you hear bandied about is rather silly). Consequently more land is exposed - albeit that a lot of it is covered in ice, with the tundra and sub-arctic areas moving to lower latitudes.

During a warm interglacial (as now):

Sea-levels rise, drowning previously exposed areas, though less of the land is buried under ice and the tundra fringes retreat Pole-wards.

There isn't a "the Ice Age". An ice-age, such as the present one, is a series of alternating cold and warm phases.