Seawatchers are somewhere in between.
(Note - many of the links given in this Instructable are commercial in nature. I am not promoting any specific companies, they are merely examples. Two exceptions are the Royal Society for the Protection of Birds and British Trust for Ornithology, two organisations that do huge amounts for the benefit of birds in particular and wildlife in general.)
Step 1: Location, location...
Seawatching is all about spotting birds at sea. Not just coastal birds, but pelagics and passing migrants.
You need to be somewhere that concentrates passing birds into a narrower band of sea than usual, or that sticks out close to the routes used by migrants.
- Headlands, peninsulas and piers are all good for birds passing along the coast.
- The inland end of estuaries are good for birds passing over the land, but that try and spend as little time over land as possible.
- Ships. You can take specialist seawatching trips, but commercial ferries are good as well - they combine a bit of height with a position right out at sea. Try and sit near the funnel, on the top deck to get an all-round view, but a stern position can be useful, especially if birds have chosen to follow the wake. If you are on a big ferry, check your routes from port to starboard, and consider spreading groups out to get all possible sightings.
- most of the Devonian and Cornish coasts (especially West or South facing, and as far west as possible),
- the North Norfolk Coast and along the Wash,
- The West Cumbrian Coast, especially near St Bees Head
- The Solway Firth, especially the east end (the birds get funnelled by the geography).