It is possible for those with vision problems or who wear glasses daily to use contact lenses while snorkeling. It is best to use soft contact lenses, as opposed to rigid gas permeable lenses, as they will better accommodate changes in pressure underwater. However, not all contact lenses are suitable for salt water or deep diving, so it is important to verify with an optometrist.
It is important to consider that ocean water contains a lot of microscopic organisms and bacteria. Wearing contacts while being exposed to salt water can create a breeding ground for these organisms to grow, so it is recommended to use disposable contacts while snorkeling or diving. If you do keep your contacts, make sure to soak them in sterile solution for 24 hours before using them again. Doing this also provides a way to replace contacts if they accidentally get flushed out.