Which water bottle keeps drinks cold the longest?

How long are we talking here - a couple of hours or all day? For longer periods, stainless steel insulated bottles (the classic ones with double-wall vacuum insulation) are simply unbeatable - they'll keep drinks cold for 12+ hours no problem. Brands like Hydro Flask or YETI are popular, but honestly a lot of cheaper options work just as well - what matters is that the insulation is actually decent and you pre-chill the bottle beforehand. Plain plastic bottles without insulation won't cut it; those are really just for short trips.