I"m a Canon girl and always take my 70D with me on our cruises. I have the 5D Mark iii but that thing is just too darn heavy to carry when I'm on vacation (use it mostly for my business.) The 70D also has a pop up flash so I don't have to carry my speedlite with me. I've traveled with extra lenses before and they generally sit in my bag. I prefer a good zoom lens that will cover most of what I'm wanting to shoot. I'm really just trying to capture family memories and my 70D with a zoom is definitely sufficient!
You will definitely want to get off the ship at Grand Cayman. It's a beautiful island - one of my favorite places in the world.
Thanks for the thoughts... even if you're a "Canon girl"...

I understand what you're saying about the lenses. For me, I love shooting with the longer zoom unless the subject is within about 35-40' And, though I also have the pop up flash, it's pretty anemic and doesn't cover much in terms of distance. So, I have no problem taking the pair of lenses and grabbing a quality bounce head flash as well... Better to have and not need as they say.
I will most likely get off of the boat at ALL ports of call, even if only to explore the area around the boat itself.
Anyone have any suggestions for a very compact and sturdy tripod? The Gorillapod's look great, but everyone complains about them breaking and only being useful to wrap the legs around stuff (won't stand up on their own). I really am looking for something that will hold the camera so I can back away and do a selfie with the remote release.
