The absolute best sunscreen/sun lotion I've found so far is this gem - the La Roche Posay Anthelios XL 50+ Extreme Fluid. This fluid is marketed at oily and combination skin types, but I've found it absorbs well for my dry skin and does not show flaky skin when properly exfoliated. On the La Roche Posay website, the product claims to have an impressive amount of good qualities including: broad spectrum sun protection, non-comedogenic properties, paraben and fragrance free, and photostability (causes no flashback).
I use Anthelios on top of SPF free moisturiser and under primer as well as massaging it onto my neck and shoulder areas when necessary. The formula is alarmingly fluid-like at first, but you learn to control how much comes out of the nozzle and spread it over your skin as this does absorb reasonably quickly.
In all I have found that it lives up to all it claims, although I can't tell how long it actually lasts. Still one should always carry around and reapply sunscreen at least every 3 hours during summer. The compact design of Anthelios Extreme Fluid allows it to fit into most bags and makeup cases. I have not tried to use this in water environments but I imagine it would not last very long as it is a water based product.