Can I patch a pool liner leak underwater myself?

Yes, you can fix most small leaks in a vinyl liner without replacing the whole thing. Find the leak with pool leak dye, clean the area, then use an underwater repair kit with a two-part epoxy or glue patch. Press it on firmly, smooth out air bubbles, and leave the pump off for 24 hours. Don’t bother with duct tape or silicone caulk—they won’t bond to vinyl underwater.