This may or may not apply to the Verizon question, but when we go to Mexico, I call Verizon and get their international plan for my BB. I put in code 228 (I think) just before we leave. The charge is $35 but is prorated. When we get home, I call and cancel the plan. This way I get my emails, etc. without an outrageous roaming charge. Call Verizon, they are really nice and will walk you thru it. Make sure you confirm that you can cancel when you get home.
Envious of your cruise!