Non-marking as well as non-slip soles, please. Especially if one plans to play on boats belonging to others. Nothing worse than leaving black streaks all over gel-coat for someone else to scrub off. I still love the Sperry Top-Sider ( and yes I've had more than a few pair of their less-expensive knock-offs that for years were made in Wilton ME). All of those mocs fit better after a few soaks in salt water.