Non-divers should not feel left out, as good snorkeling is available close inshore at various spots around the island. Perhaps the two best areas are Mushroom Bay on the west coast, and the mangroves on the northern tip. Equipment can be hired from your hotel or on the beach, and depending on the quality of the gear, you should expect to pay Rp 20,000-50,000 for renting a mask, snorkel and set of fins.
If you fancy getting further offshore, dive shops may sell you a snorkeling space on a scheduled dive boat, subject to availability. Also, local boatmen are willing to take you by boat to various snorkeling spots. Depending on the number of snorkeling spots you want to visit, a boat trip can be arranged for about Rp 200,000-300,000 (including snorkeling gear).
An enjoyable snorkeling spot reached by boat only is along the coast of Nusa Penida, with Crystal Bay being especially rewarding. There is a current along this coast. The boatman will drop you off at the beginning of the current, and you can drift with the current while snorkeling along the drop off wall with beautiful coral and loads of fish. The boatmen will follow you and pick you up at the end of the current.