My girlfriend and I went to Oahu for spring break (end of March). Though I have been there many times, it was my gf's first and we decided to do something a little different. So, a shark encounter was it! WOW!!! This is sooooo worth it. We booked the latest time available which is 1030 and I would recommend you do the same. Because it is the last slot available, they said they usually allow more time with the sharks. Arrive at the bay and the boat will come pick you up. The captain and his assistant (forgot names but both really friendly) take role and explain things to you about safety. On the trip out to the waters (about 4 miles north of the bay) they provide lots of educational information about the sea life in Oahu. Upon arrival to the cage, they go through a couple more safety procedures and get you snorkeled up and in the cage. Sharks everywhere!!! even watching the sharks from in the boat was way cool!
this is a lot cheaper and more thrilling than swimming with a dolphin for 30 minutes at the Sea Life Park!
Definitely doing it again!