There should definitely be a way to swim in water faster. It is annoying trying to train on water pokes because of how slow you swim. Maybe a Depth Strider upgrade for your running shoes or something. This would help a lot with fighting in water.
I fully agree with this one. Training in the water takes a very large amount of time. Sometimes, there could be a pokemon you really want to encounter, but it will despawn because of how slowly you move in water, even though if it were on land, you'd have plenty of time. Swimming in water cuts movement speed in half when compared to walking on land. Depth Strider reduces how much water slows you by 33.3%, so Depth Strider III would make moving in water just as fast as on land.
YESSS I get so frustrated when there is a Pokemon right in my sights and despawns because I was going so slow!! I think this would be a great little update
I've been recently trying to complete the pokedex and catching water type pokemon is the hardest. They really need to add depth strides on the boots like they added speed 2.