AT&T has international data plans for the iphone
at $100/100mb, $200/200mb, and, recently, $500/500mb (nothing between 200 and 500). Otherwise, without the plan (or over the limit) just shy of $20/mb!!!
WHEN you have wifi
, you can access data at whatever the cost of the wifi
(zero to included in a mooring
or dockage fee to whatever the provider offers).
Text messaging is separate; I think something like $10 for 50 messages but don't quote me
I have struggled to keep it to 200mb/month, though if I ONLY did NOAA, Windfinder and email
itught be sufficient.