High humidity can turn your expensive DSLRs and lenses into fungal science experiments. But here's one solution that can protect your gear.
If you live or work somewhere with high humidity, you might be well aware of how easy it is for your camera gear to get covered in fungus and dust. This is especially an issue for lenses because when dust particles are introduced to moisture inside of a lens, a fungus grows that can cause irreversible damage (called "etching") to the glass, affecting image quality.
One way of combating this is by storing your DSLRs and lenses inside an electronic dry cabinet. These things regulate the relative humidity inside the enclosure to ensure that your gear isn't being exposed to excessive moisture, dirt, or dust while being stored. You can find a few of these units on B&H and elsewhere from manufacturers like Sirui, but Ruggard recently came out with two cabinets that come in a large 80L size ($340) and a small 30L size ($130). The dry cabinets use a TE Cooling Wafer to regulate humidity, have rubber-sealed lockable doors, and have a dimmable LCD display.
There are certainly other cheaper ways to protect your gear against fungus, like keeping some silica gel packets in your camera bag or storing your gear in a box with a UV light, but some solutions are simply not effective or powerful enough for those that live or work in areas with really high humidity, like Florida, Thailand, and Singapore.
I learned this the hard way when I found that my favorite prime lens was growing some fungus. I live in the Pacific Northwest, a place where you have to actually look up the dew point and humidity to really know how much moisture is in the air (because it's rarely ever "feels" humid), so I never thought to protect my lenses beyond throwing a few silica packets in my gear bag.
So, be sure you know the climate of your area before making a decision on how to protect your gear from moisture. If you live in an arid place, cheap silica packets might be totally sufficient. However, if you live in a humid place, you might want to think about getting yourself a dry cabinet (or paying a professional to clean your lenses when they do grow fungus).