We visited Mendenhall Glacier as part of an "Explorer Tour" in mid-June with perfect weather. From the port, it's a short 15 minute drive by bus to the entrance of the park. A Visitor's Center sits at the base where a short video can be viewed showing the history including time-lapse video. There are also several trails that are fairly easy for anyone to walk (most are paved). You can get close to the waterfall just to the right of the glacier but you can't walk on the glacier itself. We were told there are very few options to get to walk on the glacier unless you book a helicopter flight (very pricey). Never-the-less, we still enjoyed our close up view after walking the trail to the end. This should be on everyone's list to things-to-do while stopping in Juneau.