Have you ever been on a Carnival Cruise to Cozumel during late December from Galveston? Any advice?

Just_Wondering asked:

I returned from a cruise to Cozumel from Galveston yesterday and it was absolutly amazing! So, My dads 60th birthday is December 27th and we think it would be a great idea for a family/birthday trip. I have no idea what to expect for weather, type of crowd cruising during that time, water conditions, etc. Do you have any suggestions, personal experiences, advice about cruising to Cozumel in late December/ early January?