Abstract: A bathtub liner apparatus includes a flexible floor sheet member which includes a top surface and a bottom surface. The flexible floor sheet member includes a drain channel extending from the top surface to the bottom surface. A quantity of adhesive is applied to the bottom surface of the flexible floor sheet member, and flexible projection members project upward from the top surface of the flexible floor sheet member. The flexible floor sheet member may be comprised of a closed cellular foam material The adhesive may become tacky when wet. The flexible projection members include a main crescent-shaped projection member projecting from the top surface of the flexible floor sheet member at a location distal to the drain channel. The main crescent-shaped projection member includes a projection-drainage channel.