If you don't care to bring a shovel with you on your hike (because your cache is buried), then maybe camouflage is an option.

I use a short length of 4" PVC water main pipe with caps. Put an end cap on the pipe, then put a 6" coupling fitting over the pipe (it should slide along the length of the pipe). Get a piece of string and tie or tape it onto the items you want to cache as you shove them in the pipe. This helps to get them out again. If you have empty space left, you obviously didn't pack some of your favorite treats (caramel popcorn, extra candy bars, bigger bag of GORP). Then put the other fitting on the open end and tamp the whole thing tight. It should be fairly water and airtight already, but if you want you can add a bit of wax to the ends before putting the caps on. The 6" coupling is there to let you take the caps off by sliding the coupling into the caps.

To remove animal temptation, spray the whole assembled pipe with chlorine bleach (won't damage the PVC and scavenges all the organics). If you keep these pipes short (2 feet or less) you can fit them in a pack easily so nobody is the wiser as you take them to the cache point. A 2-foot pipe has about 150 cubic inches of space inside. If you need more space, make more pipes.

You can get creative here and make the pipe look like a broken off sapling. Then you plant one end in a small hole and leave the rest above ground. I've wrapped one in cedar bark and then stuffed a 4" round sawed from a broken tree limb in each end. It looks just like a chunk broken off of a cedar limb, and I hid it next to a fallen cedar tree. Just don't hide it in an area where someone may collect firewood!

If the area is near agricultural land, you can actually just leave the pipe "au natural" and shove it into a ground squirrel hole in the side of a hill or leave it just lying on the ground. People will assume it's an irrigation pipe and leave it alone. It's also small enough that you can dig a shallow trench - if someone digs because the ground is disturbed and they find a pipe - they'll stop. I prefer just to find some bushes and place the pipe in them - after wrapping some camo fabric loosely around it. It really helps if you know what the intended cache area looks like. Then you tailor your camo to the area.

Of course, the bucket does work - I just was burned once when one got "muggled" - it had been opened, food gone except for two cans of beef stew, and the remaining stuff scattered around. I've never lost a pipe - it's just not something people see as a container, and since it tightly seals the contents, animals leave it alone too. I did misplace one once. When I hiked through, there was about 6" of snow on the ground and I couldn't identify the clump of bushes I hid it in (the days before GPS). I did find it 5 months later after all the winter snow melted. The contents were still perfect!