78 Inch Dia Round Hot Tub Mat, Large Washable Above Ground Protector Pad Wate...

You don’t need to mop the floor after bathing. Inflatable hot tub mats can also be used outdoors, like pools mat or barbecue mats, preventing your hot tub and pools from mud. The mat can be cut into an appropriate size if you find the mat is too big.

eBay