Good on you to get there before the glaciers are gone. That was forecast to be by 2020. I was there (US) a couple of years ago, during the last week of July during a similar snow year. Many of the high trails had just melted out at that time. Get trained in proper bear
etiquette and use of bear spray prior to going.
As for the not-to-be-missed, the park will no doubt be quite crowded at high season. Just follow the crowds. They cannot be missed. I was quite the (unintended) celebrity myself, shooting with a 5x7 view camera. Or, let one of the locals be your guide
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