No major museums out here of course, but a lot of small and charming museums explaining local history, geography and wildlife. And how they have improved over the years, and made themselves more child friendly. In alphabetical order of anchorage:
Achnacroish, Lismore: Gaelic Heritage Centre, telling the story of Lismore
Bunessan, West Mull: Ross of Mull Historical Centre
Dunstaffnage, Lower Loch Linnhe: Ocean Explorer Centre
Easdale, Firth of Lorne: Folk Museum for slate and other things, and the Slate Islands Heritage Centre
Fort William, Upper Loch Linnhe: West Highland Museum
Glenmore Bay, Loch Sunart: Ardnamurchan Natural History Visitor Centre (may well be closed)
Port Charlotte, Islay: Islay Nature Centre, very hands on stuff for kids, and the Museum of Islay Life
Kinlochleven, Loch Leven: Aluminium Story Visitor Centre currently closed for refurbishment
Oban, Firth of Lorne: War and Peace Museum
Port na Moralachd, Lismore: Gaelic Heritage Centre telling the story of Lismore
Tobermory, Sound of Mull: Mull Museum, check out the tawse (that strip of leather for beating the hell out of a naughty child's hand, in the (good?) old days of course).
Ulva Ferry, West Mull: Sheila's Cottage