WWII-era cruisers were largely "belted cruisers"

From the 1920's on, most cruisers had such a narrow swatch of armor that they had become "belted cruisers", along the lines of the Orlando class ships. The belt was covered by a deck, and the belt was almost submerged, being essentially one deck high. The British cruisers tended to have more coverage, in that they had armor that rose above the machinery spaces on the side, for a shorter distance than was covered at the waterline. As ships were increasingly overweight, much as in the 1880's, the belt was almost totally submerged. In the British case, the only part that had much above-water coverage was that above the machinery spaces. You can see it on the Edinburgh, Southampton, and Dido class ships, as well as others.