A floatation mattress assembly for sleeping upon or floating in a body of water includes a mat that is comprised of a resiliently compressible material for sleeping upon. The mat is comprised of a buoyant material to float on a body of water. The mat is structured to have the ornamental appearance of a flip flop article of footwear. A first tube is pivotally coupled to the mat, and the first tube is positionable in a deployed position or a stored position. A second tube is coupled to the first tube and slidably extends through the mat. Thus, the first and second tubes have the ornamental appearance of foot straps on the flip flop article of footwear. A net is removably attached to each of the first and second tubes. The net forms a hemispherical dome over the mat when the first tube is positioned in the deployed position.