The worst one I ever did was Calais to Dover in a howling gale. We couldn't dock for hours and hours as the weather was so bad so we were on the bloody thing for six hours or something.
This happened to me too, sometime in the mid-70s I guess. I wonder if ships were worse or weather prediction's better. Or we were on the same boat
I love a ferry. I think most of the ones I've been on have been mentioned. I go from Portsmouth - France or Portsmouth - Spain at least once a year. Always means it's the start of the holiday; on the boat; dog in the kennel; bags in the cabin; lagers and 'entertainment' in the bar
Then a lovely swaying kip with no wake up (to Spain) or a disgusting non-switchoffable, ever increasing volume alarm at absolute bastard o clock (to France). But then you're on holiday so it doesn't matter.
Used to go from Dover/Folkestone to France every year in the mid-70s to mid-80s, ("roll/-on/roll-off/rollover").
There are a couple of little ones fairly local to me: the Hythe Ferry (sadly not currently running due to issues with the pontoon). Has an added bonus:
Arriving at Hythe Pier, board the World's Oldest Pier Train (official Guinness World Record) and after the short ride of 640 metres (2,100 feet) you will have travelled along one of the ten longest piers in the British Isles
Also the Hamble - Warsash ferries - "the pink ladies":
Between the two waterside villages of Hamble and Warsash, a little bright pink ferry plies back and forth. We take a look at its 500 year past and bright future with legendary ferryman Ray Sedgwick and current owner Mike Lindsell.
www.bbc.co.uk
Other great ferries I have loved:
La Ceiba - Utila, Honduras - saw flying fish!
Panajachel - San Pedro, Guatemala (I think
Voley's done this one?)