In the novels when Bond isn't sporting a suit and dress shoes, he goes casual with a pair of black leather sandals. Sure they aren't as versatile as boat shoes, but then again you aren't always going to be on a boat.
Aldo MAPALO $100.00 aldoshoes.com
John Varvatos black leather 'Kenmare' thong sandals $94.00 bluefly.com
To Boot New York Men's Desoto Sandal $83.22 endless.com