The North Face Women's Base Camp Flip-flop (Petit Four Blue/Deep Water Blue):

These are awesome: they have a proper sole with grip that means you can actually walk on ground that isn't perfectly flat without slipping all over the place, likewise they work when wet and even better than all that, the footbed has nobbly bits (technical term) that are like a mini-massage. Worth every extortionate penny.

The North Face Women's Base Camp Flip-flop:
UPPER: PVC-free PU-coated synthetic strap with soft PU binding and jersey lining
BOTTOM:Extra-cushy, egg-crate-inspired EVA footbed with anatomical arch support
Rubber outsole
Weight: Average 350g pair