Fast boats run from Sanur to Nusa Lembongan throughout the day, with the crossing usually taking 30 to 45 minutes. Most services land at Jungut Batu or Mushroom Bay; check your landing point before booking, as it affects where you should stay.
Boats also connect Lembongan with Nusa Penida and the Gili/Lombok routes through some operators. Seas can be rough in the wet season, and cancellations are possible when swell is high.