There are countless tour companies offering trips to the islands. We booked through a hostel that advertised tours out on the beach early in the morning. Our tour was at 8am (one more went out at 10am) and cost 25 soles per person. An additional 15 soles each was required for entry to the islands, part of the national park, and 5 soles each admission for the dock. Our park tickets allowed us to bike in the national park the following day without paying again.
The tour itself lasts about 2 hours. Our guide gave all information in both Spanish and English. Since we did the 8am tour, it was a little chilly when the boat really got moving. However, the 10am tour seemed to be more crowded and we'd heard the water gets choppier later in the morning.
All tours start off with a stop at the 600 foot tall candelabra carved into the sand. It took us about 15 minutes of speedy boating to reach the candelabra, and another 15 or 20 mins to the islands. Once we reached the islands, we enjoyed beautiful rock formations with sunbathing sea lions sprawled across every ledge. Our guide pointed out Humboldt penguins way above us, and we enjoyed watching them waddle from afar.
Overall, we thoroughly enjoyed the tour even though it felt a little more touristy than our usual adventures. For a total of 40 soles per person, we thought it was a morning well spent.