We took the ship's tour which involved a bus ride to a dock, than a 1.5 hour boat ride thru mangrove forests at some good speeds. The ruins were very interesting as were the twists and turns speeding thru the mangroves. We really enjoyed this tour. Google Lamanai and you'll find quite a bit of info out there.
We took the Mayan Ruins of Tulum tour on a ships tour from Cozumel. It was the best Ruins we have seen. We didn't care for the 2 out of Belize or out of Costa Maya. If you can get to Tulum from Belize, thats what we would recommend.
Tulum is really small. Chitzen Itza and Lamanai are much bigger, with more and bigger buildings. Tulum is in a beautiful location though, especially when combined with Xel-ha lagoon. It all depends on what is offered by your cruise line, and where you dock.
We did the River Wallace, Altun Ha excursion through the ship. I was surprised at the size of the ruins at Altun Ha. No they aren't as extensive as Chitzen Itza, but were much larger than some we had seen from other ports. We really enjoyed this excursion and thought it was worth the money.
Im not sure what Alan liked about the Tulum ruins. I have been to all three ruins in Belize and I have been to the ruins in Tulum. In tulum, there are just a few little piles of rocks left. Nothing you can climb up, and nothing is in tack. There as absolutely no shade and we walked around for an hour and gave up. It was really boring. Sorry, Allen, but all we did was sweat and not even take any photos. Tulum as beautiful beach, but the ruins were a huge disappointment. Also, to go from Belize to Tulum will take you an entire day. You have to cross the border and then either take a taxi or a bus for around 4 hours. You would have to overnight as you would get in very late in the afternoon. From my experience, you will spend your time much better if you select ruins in Belize. Altun Ha is the easiest to get to, very close to Belize City. All tour guides are Belizean that have taken extensive tour guide courses through the Belize tourism association. Their knowledge and love of their country really makes the tours fasinating. You will be able to climb the ruins, which are in excellent condition, and you can get a great view of Belize. Lamani is more remote, but the boat ride there is part of the beauty of the trip. You will travel up and old rive to the ruins where you can expect to see monkeys and tropical birds such as toucans. The ruins are beautiful. The last one, Xunantunich is the tallest ruins. They are also well intact so you can still see the detailed cravings made by the mayans. When you climb to the top you can see as far as Guatamala. Belize is a great place to explore the Mayan ruins. You can see great pictures of all three ruins at Belize Cruise Excursions Shore Trips Guide for Belize Excursions specializing in Cave Tubing for Cruise Ship Passengers on Western Caribbean Cruises