What is the best travel bowl for hiking with a dog?

A folding bowl made from ripstop fabric with a waterproof lining or from soft silicone packs down to a few centimeters thick, clipping easily to a carabiner on a pack strap. This matters more on multi hour hikes than a rigid bowl's slightly better stability, since pack weight and space add up over distance.

A short one hour walk barely needs 250 ml (8.5 fl oz), but a half day hike in warm weather is easier with a 500 to 750 ml (17 to 25 fl oz) bowl so you are not stopping every 20 minutes to refill from a bottle.

Silicone bowls resist punctures better on rocky or thorny trails but can feel slightly less stable on uneven ground since they are lighter. Fabric bowls with a stiffened rim sit flatter on rough surfaces but are more prone to small tears if snagged on branches, so check the seams before a long trip.

A bowl with a built in carabiner clip or a loop for a strap saves fumbling in a pack pocket at every water break, which matters on a trail where you want to keep moving. Testing the clip's grip before a long hike, rather than on the trail itself, avoids losing the bowl somewhere along the route. Rinsing the bowl at a stream or with carried water before packing it away also stops leftover food residue from attracting insects inside your pack on the walk back.