We stayed at Poseidonia apartments and booked our day trip at the reception. It was all very straight, the receptionist booked the trip for us and gave us our voucher.
The coach picked us up in front of the hotel at the scheduled time and it was a nice comfy coach with air conditioning. We stopped at lots of hotels to pick up people and then Mano's gave us instructions on how the day would be. We were dropped off the harbour and got into Glaro's boat before other tours/people, which was quite lucky!
The boat has 3 levels, the top levels has places to sit and sunbathe, we were lucky to be the first tour to board so we were able to get a place at the roof top to sunbathe, people who got in after us didn't have the same chance and had to stay in the bottom/1st level with no chance to sunbathe so make sure you get there early otherwise you won't have this chance.
The trip was very pleasant, it was really hot and we had to go downstairs a few times to get some shade because the sun can get overwhelming sometimes. We stopped at 4 different locations and had time to jump in the water and enjoy the extremely beautiful locations (bring your water goggles cause it's quire handy).
They offer lunch and it's nice traditional Greek food and we loved it! There is also a small bar in the boat where you can buy ice cream, drinks and some snacks so it's handy if you didn't purchase the lunch ticket.
I would recommend the trip to people going to Rhodes, it's a full day trip (08am to 5pm) and it's worth the money!