I installed a WiFi system on Dreamer about 12 years ago and used it extensively on the west coasts of Canada, US and Mexico. It had a range of up to about 5 miles over the water and back then, many of the private network connections were not encrypted or protected and we would often slow down when we spotted a cluster of houses on shore to see if we could connect and download our emails.
We also used it in various marinas that had WiFi and created our own network/hotspot onboard for both laptops and our main boat computer and of course, now one can also access such network with smart phones and tablets.
It worked quite well.
I'm sure the systems have improved since then.
Here is a link to help you in your research.
Let us know what you learn and what you choose.