I'm not a great traveller on water, so I try to avoid. It's been a good age since I've been on the shields ferry. The last ferry I used was the Santa Pola - Tabarca ferry in the Mediterranean. Thought I'd give it a go as the sea looked nice and calm, but it ended up rocking for half an hour till I got there. Spent the few hours on Tabarca dreading the trip back in the end!
But that being said, it's a great little island and the weather ain't bad over that way either.

Few details here if anyone is interested;
http://www.discovercostacalida.info/en/W...a-Tabarca/
http://goo.gl/maps/KEFzW