In general you want to keep your feet dry. There are a variety of ways you feet can get wet. The most dramatic are river crossings, followed by rain, snow, and slush. The final issue is sweat from your own feet (feet can dissipate up to 2 cups of water in a day). There are several approaches people use in an attempt to keep feet reasonably dry: There was an article at BPL about spring footwear that is appropriate for cool, wet conditions when there is a real risk of the temperature dropping from cool to cold.
Use footwear which is highly breathable and quick to dry (sandals, water shoes, or trail runners with a lot of light-weight mesh) on the assumption that their feet will get wet, but then will dry quickly. A slight variation of quick dry that is comfortable when wet. Some people have found that using Neoprene socks can keep feet comfortable because the neoprene foam provides effective insulation and doesn’t bind when wet. Modest wetness dries overnight, but soaked shoes don’t dry overnight. Wet trail runners being worn while active without additional external moisture will mostly dry in a reasonable amount of time thanks to body heat plus the pounding of the feet which drives out moisture. Mostly-dry trail runners can dry overnight.
There was some data about time it takes for a variety of different types of trail runners to dry in the open air in the forum posting about Inov-8 & Timberline Delerion (and other fast drying shoes) and a second posting of fast drying shoes. Bottom line is that shoes in a cool location take a long time (>15 hours) to fully dry. On the other hand, shoes can dry significantly in just a couple of hours if you feet are active and you don’t have external water sourced to deal with or if the shoes are sitting in bright sunlight. BPL did a nice article about water weight gain and loss in lightweight shoes. There are a number of light weight trail runners that will absorb between 15-30% water weight after being soaked, and be down to 4-10% weight gain after a couple of hours of use. So it is possible to soak your shoes in the mid-afternoon, get them mostly dry by the end of the day, and see them fully dry over night.
It should be noted that in some environments that “quick” dry will never dry. Some of our friends down under report that between rain and river crossings their feet are wet until they go to bed. What they have reported as that so long as they are using light weight, flexible, highly breathable trail runners which fit well, and a good pair of socks that they have avoided blisters. In these sorts of conditions some people have had very good experiences coating feet that are going to be continuously wet with Hydropel.
I have found waterproof breathable socks such as Rocky Gore-Tex oversocks or SealSkinz tend to be more breathable than “waterproof” boots when worn inside highly breathable trail runners. I have also found these socks to be more waterproof than the boots and that I can dry the gore-tex socks over night (skinskiz not so much). When wearing waterproof socks you don’t need to worry about your shoes getting wet, because you feet are protected inside the sock. They also keep your feet clean… often mesh trail runners let a lot of small dirt particles in. It’s possible to seal the top of the socks so they can be submerged and keep your feet dry. My experience is that unless it’s cool (say below 40F) gore-tex socks are too warm and my feet sweat more than the socks can breath.
One of the most common approaches is the use of waterproof boots. For example, boots with Gore-Tex liners or leather boots with Snowseal or Nikwax to the outside of your footwear. While these approaches will keep external moisture at bay for a time (my experience is for a few days at best). Once the inside of boot gets wet, it stays wet for a long time. Alas, while good at keeping external water out, they also tend to hold water in. You feet will stew in the sweat they generated. Waterproof boots don’t typically have when crossing water because the water will flow in over the tops.
Extra Shoes / Barefoot
Some people focus on dealing with external moisture when fording streams, walk through the surf, or otherwise immerse feet in water. The most common approach is to carry a spare pair of footwear such as sport sandals like Tevas which often add 1.2lb to your load or the slightly lighter Crocs. Some people use minimalist shoes or sandals mentioned above for water crossing. Sand Socks Grip Socks look like a good option. The lightest options (and one of the cheapest) I have found are nylon mesh pool shoes which provide modest protection to the soles of my feet and some slight traction. I have known people who wear just socks but I don’t think that makes a lot of sense because their traction is worse than bare feet and they offer little real protection. Some people do water crossings by taking their shoes off and going barefoot. This is a low weight option, but runs the risk of bruising or cutting your foot. I do go barefoot for crossings when the crossing is the only reason my feet would be wet and I am confident that the riverbed doesn’t have a lot of sharp rocks.