Fast enough for zoom calls

Starlink has several levels of maritime service. For $2,500 initial payment and then $250/month you can get 50 GB out in the ocean and unlimited by land. This is what we will use on our first seasteads. See also Starlink FAQ, Wikipedia on Starlink, and sailingwawen.com collected some info on starlink for boaters.

There are some other services that may now or some day be competative with Starlink:

OneWeb
Kymeta Seems like $30,000 initial then $735/month for first 10 GB.
KBH has maritime VSAT service.
ViaSat3 Geostationary satellite with terabit bandwidth - claims better economics than LEO sats- Q1 2023
Telsat plans a 292 sat constellation
Amazon Kuiper has launched a few sats so far

Cell Phone from space

AST SpaceMobile plans to provide sat service to regular cell phones for places within about 19 degrees from the equator maybe as soon as a year from now. This covers Anguilla and much of the Caribbean, so it could be what seastead.ai uses first. As it is supposed to work with a regular cell phone, I expect it would work well with some sort of external antenna that was aimed up. Not sure there are such antennas for boats yet, but expect there could be soon.

Starlink is also working on service for regular cell phones. The service will be able to provide voice, messaging, and basic web browsing at theoretical peak speeds of up to either 3.0Mbps or 7.2Mbps peak upload and up to either 4.4Mbps or 18.3Mbps on the downlink. Maybe starting around the end of 2023. This might be included in many companies regular cell plans, so practially free. T-Mobile is onboard.

Fast enough for email

Iridium Go has wifi boxes for about $1,000 but connection is only 2.5 kbps and costs about $1.50 per minute. It seems limited to "approved apps" and so may not be a general solution. I would rather they just sell communications bandwidth and not try to control how you use it. This is no where near good enough for most people to work from home.

SpaceX bought Swarm.space which has a $60/year data service giving 750 messages per month of 192 bytes each. For testing models or even full scale seasteads this might be interesting.

Emergency or very short message

Apple iPhone 14 includes an Emergency SOS feature

Links to pages looking at maritime internet options

Boat to Cell Tower Systems

Early seasteads will probably spend most of their time within 20 miles from shore. There are antenna/wifi systems that boaters use for this. They install a special antenna, get a cell data chip, and then the box provides wifi to people on the boat.

Go to seastead.ai.