by nite0wl » 2 Jul 2015 20:08
As others have mentioned this is one environment where you really need to weigh security versus environment and cost.
Abus has a series of Marine padlocks in various sizes which are pretty well suited to the environment you describe and Abus does a decent job of selecting keyways and pinning to make their padlocks difficult to pick or otherwise bypass. The all brass construction does mean that destructive techniques may be somewhat easier to execute. The pricing of these locks reflects their middle-ground status, survivable but not likely to stop determined or prolonged attacks.
Pac-Lock makes a similar type of lock with a steel shackle which provides slightly more protection against destructive entry and provides somewhat better bypass protection but their pick resistance is likely to be roughly equal to the Abus locks at best.
Outside the US Masterlock makes a specialized version of their 140 family of solid body padlocks for marine environments or the all brass versions of their iconic laminated body locks (#2,#4, and #6) are also available. These provide decent protection against destructive attacks and Masterlock has been getting better about bypass protection (they are still no more pick resistant than any of ML's low end products, which is to say, not at all) but their most compelling point for you would probably be their price which will usually be better than the higher quality and higher security locks.
Some of the high security (or at least high quality) locks suggested by earlier posters such as the Abloy or Best are very good locks (the Abloy probably provides the best suitability for the environment you described) but even if you find locks and cylinders at a good price on the secondary market obtaining spare/replacement keys and other costs of maintaining those locks will still be much higher than the brands suggested above.
