Now this is a cool website. I'll quote the site.
A group of ShipPlotter enthusiasts bring you live vessel movements from around the Irish Sea (and further!) derived from AIS data. Click on the map to see the individual ships, their statistics and photos.
It looks like real-time ship movements around the UK.
I picked the map for the Sound of Mull and took a screenshot.
You can see the four CalMac vessels. The Hebridean Princess off Tobermory; the Clansman in mid-Sound heading to the Western Isles, dodging the Loch Fyne which sails from Lochaline to Fishnish; and the Isle of Mull going to Craignure. The green vessel is moored at Glensanda Quarry.