covered depth depth indicators distortions lines platform pool pool floor rippling rubberised surface surface swimming pool tiled surface water angled artificial blanket diagonal diagonally diagonals picnic picnic-blanket ribbed ribbing rubber rubberised rubberized surfaced surfaces surfacing texture textured textures underside uneven variations varied various waterproof appearance cloth color colored colorful colors colour coloured colourful colours fabric fingers gloves green grip helpful materials multi-purpose non-slip pairs protection protective rubber-coated rubbery shape shaped shapes useful work-gloves