There are many levels of birdwatching, from the dedicated, high-mileage twitcher to the casual glance at the visitors to your bird table.

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.

UK locations that are good are;

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).

If you can manage it, you should make time to visit one of the BTO Observatories around the UK coast.

Step 2: ...location

Wherever you end up, you can do a bit of seawatching, even if you are not in one of the "ideal" locations.

You need to be somewhere with as much visible ocean as possible.
You need to have some height, but not too much - too high, and you will lose low-flying birds against the surface of the sea, too low and you will lose swimming birds amongst the swell.

Pier heads, harbour walls and low cliffs are all ideal. My usual locations are Ness Point and Workington South Pier (which happens to be the western end of the C2C Cycle Route, so I occasionally get cyclists asking if will take their photos as the arrive or get ready to leave).

Step 3: Timing.

There will be days when you go seawatching and all you see is the sea.

You can, however, improve the odds;

Going when the sun is setting or rising over the sea (depending where you are) can increase the chance of seeing birds against the sky.
Onshore wind, the stronger the better, will bring pelagics closer to shore.
Avoid heavy rain and fog. You won't see anything.
Check birding websites for migrations - Spring is good, Autumn is better. Winter is OK, Summer is poor.
Tides will change the location of roosting or feeding birds, especially if there are open expanses of sand or mudflats (Check the web, or consider investing in tide tables. Tables for individual locations are quite cheap, and usually available from Tourist Information shops or harbour masters).

Consider going at night - you won't see anything, but some species migrate at night, so you may get to hear their calls (I'd love to hear a Manx Shearwater in the field).

Step 4: Equipment.

The very minimum you need is a pair of decent binoculars.

I won't recommend a particular kind, but it is advisable to stick with brands you know. My father uses Swarovski Optics, I use RSPB. It is a simple fact that you get what you pay for, and you should buy what you can afford. Speak to a specialist dealer when selecting, then consider buying specific models online - ex-birders sometimes sell their gear at silly prices. Joining the BTO sometimes gets you a free pair of binolculars, and some birding magazines sometimes offer binoculars as an incentive to subscribe - check what offers are available.

A spotting scope and tripod are as important as binoculars, because of the greater magnification and steadier view. Again, you get what you pay for - I use a second-hand Opticron scope. New scopes can cost as much as £3,000 ($5000).

_{If you want to get into birding in general, with seawatching as an aside, spend as much as you can on binoculars, then see what you can afford for the scope after that. Some dealers will do you a deal if you buy bins, scope and tripod all at once. Consider service as well - Swarovski optics are among the most expensive available, but they will often repair registered owners' equipment for free (my dad uses Swarovski - his tripod got dust in the mechanism in the Gambia, Swarovski said "send it in, we'll clean it, no charge").}

Bird books. Don't go by price, go by content. You need at least decent national guide, plus a book on identification by behaviour would be useful. Check online bookshops and ebay, but, if you can afford it, I always recommend buying from a bricks-and-mortar local bookstore - you cannot beat the helpfulness and intuitive advice of an actual human being.

My personal bird books are:

RSPB Birds of Britain and Europe (Rob Hume)
Flight Identification of European Seabirds (Anders Blomdahl, Bertil Breife, Niklas Holmsröm)
Shorebirds of the Northern Hemisphere (Richard Chandler) (Also useful for continental North America, Northern Africa and Asia)
Identifying Birds by Behaviour (Dominic Couzens)
Birdwatcher's Year Book 2010 (an anual publication, which includes record pages for keeping your year and life-lists up to date)

I also read Birdwatching magazine (link is an advert), and sometimes Birdwatch magazine.

Notebook and pencil.

You may not recognise a bird straight away, and it surprising how much detail does not stick in the memory. Notes and sketches will be invaluable to later identification, no matter how badly drawn (they're only for you, after all). You will probably also end up creating a life-list, year-list or site-list, so will want to record the dates, times and conditions you see each bird.

Camera.

Not so important, but you may want to snap off record shots for later identification.

Protective clothing.

You are going to be standing still, beside the sea, in many weathers. A decent long coat, hat, maybe gloves will all be useful at some point.

Home comforts.

Seawatching can take hours, so some people like to sit down with their tripod lowered to be used from a camp chair, with a flask of hot coffee to hand. I recommend using an "unbreakable" stainless steel flask, in case it gets kicked off a cliff. Sitting down can also make it easier to take notes. It is possible to buy special folding hides that include a chair, or you may use a fishing tent or fishing umbrella.

Optional extras:

Dictaphone - to record observations without having to take your eyes off the birds. There is at least one model designed to fix to your binoculars.

MP3 or MP4 player - it is possible to buy recordings, digital stills and video clips of the birds you are likely to see.

Camera mount for your tripod - many birders are getting into digiscoping - taking digital photos through their spotting scopes. It can be an expensive hobby.

Step 5: What to Do.

Look at this, we're all the way to step five before we even look at any birds!

The actual act of seawatching is very simple; to stand or sit and watch the sea and sky for birds.

There are three areas to watch - the open sky, the band of sea and sky forming the horizon and the surface of the sea itself.

Some, very intense people choose to sit and focus on a small "slice" of sea and sky, waiting for something to cross their vision.

I prefer the three-stage method; eyes, bins, scope:

Scan the sky, horizon and sea with bare eyes, looking for flashes of movement.
If you spot something, follow up with the binoculars for a closer look. When switching from eyes to bins, stay focussed on the object of interest, and bring your binoculars to your eyes. Do not look down to meet your binoculars coming up, or you will lose sight of the bird and have to waste time hunting for it again.
If it is distant, hard to identify, or simply quite interesting, switch to the scope for a closer view.

Scanning the sea should take longer than scanning the sky, as things will be bobbing in and out of view in the swell.

I often merge stages one and two, scanning with my binoculars.

If you are a note-taker, take your notes as soon as you see the birds, otherwise the details of one can merge with the next.

One of the most important aids to bird identification is size, as many seabirds have similar outlines and silhouettes.

Unfortunately, one of the hardest things to judge when looking at a bird in open sea or sky is size. If possible, compare the bird to objects of known size at a similar distance, such as lobster-pot buoys, people in boats, or people walking along the beach.

Step 6: Jizz.

You will not always get the chance to seawatch.

The weather might be too bad, work and family commitments may get in the way, but you can still work on your knowledge of jizz. Jizz is a birding term for "general impression of shape and size" . There is a myth that is was acquired from WWII aircraft spotters (hence the illustration), but the term pre-dates WWII by over two decades. With practice, how a bird acts is as much a key to identification as what it actually looks like.

A midsized dark bird flying between bushes at ankle height will be a blackbird. The similar bird in a small flock overhead will be a starling.

Browse your birdbooks, especially any specific identification guides, getting to know the key characteristics of the birds you are likely to see. Do not neglect the commoner species - if you are familiar with them, then rarer birds will be more likely to stand out.

Use your video guides, or go online (see the next step) to watch video clips of the birds in flight, swimming and on the ground. Look for patterns in the wing-beats, or how the wings are held (stiff, curved, droopy?). What is the flight-path like? How high does it fly? Do you see flashes of lighter or darker patches?

All of these will give clues to allow quick identification of birds you see. The more familiar you get with jizz, the quicker you can spot a new or rare species, simply because it doesn't "feel right" - if the jizz isn't familiar, get as good a look as you can, as quickly as you can.

Step 7: Birding Online

That's it, really.

You may want to chat to other seawatchers - ask them what's about.

You may want to get involved in general bird conservation, surveys, bird ringing, or just general chat.

These days, that will inevitably involve you getting online (these links are all UK-biased), both for information and to acquire equipment. Some of these sites could spare you the initial expense of a birdbook.

The RSPB site has news and views, guides to reserves, and a good set of pages about specific birds, including video clips and audio recordings of many species.
The British Trust for Ornithology is slightly more "hard core" - you can volunteer for surveys of various kinds, as well as joining in ringing birds at observatories. They are also the guardians of the definitive Bird Atlas of the UK.
BirdGuides has a lot of up-to-the-minute news, including sightings, photos of rare species etc. Free registration gets you a weekly email of news and bird sightings around the UK. As-they-happen alerts to twitchable birds requires a paid subscription. (I only use the free services).
BirdForum is a free forum, chat about birds, post photos, get help with identification etc. Most members are quite welcoming, but some are very scathing with new members, or members who make mistakes. There is a definite pecking order. The site also boasts galleries of birds, a wiki-style bird-related encyclopaedia, blogs and equipment reviews. Membership is international, so you can get help with planning trips as well.
Seabird News is a fairly hard-core group on Google, which you can read without joining.
If you are not in the UK, and want to find a more local birding organisation, try checking the Birdlife Partners list as well as search engines.
Finally, and potentially most promising, there is Collins Birds - the site is not running yet, but Collins is a major publisher of birding books, and I have spoken to a couple of people who know things. It looks promising, and is going to be free. What I cannot see yet is an income source for the site (maybe paying for bird alerts?). If you visit the link, and enter your email address, you will also be entered into a draw for a rather decent pair of binoculars.

That is only a tiny taster - there are also many local groups and clubs, plus similar groups and organisations around the world.

I hope you've enjoyed this peek at one of the lesser-known sides of birding, and think about having a go yourself.