This was our second time going to Molokini but our first time on this specific tour. Because it's a smaller boat / raft, there is no bathroom and lots of wind but that can also be the charm of the trip. Because it is a smaller boat, you have more 1-1 interaction with the staff. They had the captain (person who drove the boat) plus two girls to help with the snorkeling and they both happen to be marine biologist too so they had a lot of knowledge around the fish. Also one of the girls was a freediver which was really cool. She had a lot of passion about the fish and showing you things in the water which was very appreciated.
It wasn't necessarily four hours long. For us, it lasted 3 hours and 15 minutes (we were back at 10:15am) but we also got cold while snorkeling so it did cut it short a bit and we were ready to go anyways. I would recommend some type of very light wetsuit or something so you can stay in the water longer (yes, you're in Hawaii but it does get cold after a while!).
The type of fish out in Molokini that day (Oct 2022) was cool but wasn't as diverse as it was when we visited 5 years ago. Maybe its because we were on the left edge of the crater versus the middle? Or things just change over the years? Either way, it was still fun. They provided water, juice, sandwiches and chips/snacks which was really nice.
Again, there's no bathroom so make sure you go before!
Things you'll need: a towel, reef-safe sunscreen (put it on before you come because they won't let you put it on while on the boat), sandals (as you don't wear shoes on the boat necessarily since you're snorkeling), sunglasses, etc.
Overall, we would recommend. We liked the smaller group but at the same time, did miss a larger boat with a bathroom so there's pro and cons!