Mushroom Bay is one of Nusa Lembongan's easiest beach bases, a sheltered curve of sand used by some fast boats and backed by cafes, dive shops, and small resorts. It is more convenient than wild, but that convenience is exactly why many travellers choose it.
The bay is good for a swim when boat traffic is light and conditions are calm. It also makes a sensible base if you want to avoid riding across the island with luggage, since some ferries land directly here.