There are various useful generic websites, many of which have appeared more than once on this website. Here they are in alphabetical order, with links:
The Aberdeen University Library has a wonderful collection of photographs if you want to know what this part of Scotland looked like in the second half of the 19th and early 20th century. You need to search about for 'Mull', 'Oban', Skye, Staffa etc. in the George Washington Wilson and Co. archive.
Argyll and the Isles is a very informative and attractive website, has bags of information and links to lots of things to see and do, news, comments and so on.
The Association of Scottish Yacht Charterers does what it says on the tin.
The Canmore database is invaluable. It has images and information for more than 300,000 historic sites in Scotland on the online catalogue of archaeology, buildings and other heritage sites. It is part of Historic Environment Scotland.
The Heritage Paths website has some interesting walks which are close enough to an anchorage to be doable.
The Sail Scotland website is excellent — lots of really useful information. But abit commercial with I suspect at least some text written by people wanting to promote their establishments.
If you want to know if any of the anchorages have featured in a movie then go to Scotland the Movie Location Guide. The last update was in 2017.
Undiscovered Scotland is a pretty good general site for almost everything of interest.
visitmyharbour.com has a wealth of information, not just about this area but all round the UK — tides, harbours, navigation etc etc.
Walk Highlands is a brilliant website for walks. Mind you, this is more for walkers than boaties but there are plenty of ideas there for a day ashore.
Welcome Anchorages is a useful free publication about marinas, pontoons and visitor moorings all round the Scottish and Northern Irish coasts. You can pick it up free at many chandleries, or download it. Notwithstanding the title, there is precious little about proper anchorages, and I imagine the entries are not written by independent authors. The last available edition appears to be 2020.
The West Highland Anchorages and Moorings Association (WHAM) represents the interests of west coast boaties on matters affecting anchorages, moorings and other maritime issues. Useful general background information and news.