It is easier to find a hole in your pool liner when the pool does not have any water in it. Before you fill your pool with water, you should always check the entire surface for any signs of rips or tears. Use a flashlight and do a thorough visual check of the frequently trafficked areas of your pool. It is possible to find a hole with water in the pool if you have an idea of where the hole may be located and with a set of snorkeling gear. If the hole is in the deep end of the pool, you will likely need scuba diving equipment, or hire the help of a professional to identify and repair the hole. Once you have identified the hole, you will need to use a pool liner repair kit or hire a professional to patch the hole.