I don't know how manufacturers and sellers define waterproof, but their definition is far from mine. Water and other liquids go straight through to the mattress underneath.
Waterproof Twin XL Mattress Encasement With Zippered 6-Sided Cover, PlushDeluxe Premium Quality, And Cotton Terry Surface (Fits 12-15 Inches H)
14 Review
2-Pack Twin Size Mattress Protectors With Waterproof And Cooling Features - Soft Bamboo Cover, 3D Air Design, Noiseless And Breathable Mattress Pad, Fitted For 8-18 Inch Deep Pockets
18 Review
Twin Size Zippered Mattress Protector Encasement - Premium Terry Absorbent Cover With Six-Sided Waterproof Protection - Quiet, Breathable, And Fully Washable
43 Review
Protect Your Twin Mattress With Zippered Waterproof Encasements - Twin 2 Pack Included
14 Review
Secure Your Swing With Safe And Easy Tree Swing Hanging Kit - 2000 Lb Breaking Strength And Quick 10Ft Long Strap Installation
34 Review
Black 2-Pack Of Vivere EFHTS Accessories For Hammocks
27 Review
LOFTEK LED Dimmable Floating Pool Lights Ball, 16-Inch Cordless Night Light With Remote, 16 RGB Colors & 4 Modes, Rechargeable & Waterproof, Perfect For Indoor/Outdoor, Exhibition Decor, 1-Pack
38 Review
Gulrear Portable AC Window Seal Kit - White 400CM/158Inch Hot Air Stop Exchange Guards With Zipper And Adhesive Fastener
38 Review