One of the keys for me, especially when I'm paddling, is that I want my PSK on my body, not in the boat. One nice thing about an altoids tin is that it's compact, and will fit in most of my pockets easily. I always have a kit in a pelican box when I'm in a boat, but I always have the basics on my person too. some boats are designed not to sink, but that doesn't mean they won't float away.