I've used a few different water bottles over the years, but I keep returning to my Klean Kanteens. I have two sizes and three different caps, all interchangeable. Just last night, I put three ice cubes in with some water in the larger bottle, and sixteen hours later, there was still some ice. As long as you stick with 'TK-Wide' bottles and caps, they can all be swapped around, so you can have the cap you want on the size you want. ## The Caps - Standard screw-cap - works well, nothing especially interesting about it, but it's probably the best for insulation, and feels very safe from leaking. - Cafe Cap - centre bit rotates 90° to open and close a bit you can sip through. Good for coffee, keeps it hot even with the sip bit open. A bit more hassle to take it apart and clean it. - Twist Cap - a weird one, but the one I use most. Silicone rubber straw bit pops up from the top when you twist it, and connects to a metal straw part inside. Complicated to explain, but very easy to use - twist one way and the straw end pops up to drink from, twist the other way, and it's neatly hidden away so it doesn't get touched. A bit of a pain to fully clean, but I only use it with water, so it doesn't need fully cleaning too often.