It only takes a little bit of work to turn a bamboo cane into a very practical canteen. To make a bamboo canteen you need to locate the largest bamboo you can find. Make sure that it is not split or damaged. Cut a piece of bamboo down. Cut or saw a section of the bamboo leaving a solid joint on each end. Pictured below: top, large piece of bamboo; bottom, one section cut out with end joints
Now take your knife point and begin drilling a hole in the side of the bamboo toward one end or the other. Pictured below: hole in bamboo
Bamboo has a membrane that grows inside of each section. If the bamboo is dry this membrane will flake of and mix in with any water that you store inside the bamboo. You can remove some of the membrane by dropping a handful of small stones into the bamboo, adding a little water, and shaking vigorously. Pour the water and stones out and rinse. Personally, I don't bother with this. You will never get all of the membrane out, and you will probably get some of the stones that won't come out.
Next step is to carve a plug to fit into the hole. Any wood will do. Carve a tapered plug that will make a good friction fit into the hole. Pictured below: plug carved out and ready to insert
You can call the job done at this point, or you can do as I have done and make a carrying strap. I twisted this one up out of split yucca leaves. Pictured below: canteen with yucca belt strap