Yes there are trials that lead down to the water, and they are too difficult to hike. Some parts of the trail get pretty narrow though, but that's the most you really have to watch out for.
Yes. My suggestion would be to park at Valentine's Flat entrance and take the trail to the water. Once you get there you will go down stream till the creek takes a 90 degree turn, which is a few hundred yards away. The water here is usually deep enough to swim. There is also a natural ledge on the far side that is a foot or two underwater to jump off of.
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