It is accessible with a cane The inside is definitely doable Outside may be too far to walk but you could see most of it. .
If you need a cane, use it. There is a board walk out over the marsh area that was neat. It was low tide and we saw small crabs eating and trying not to be eaten by larger crabs. Nature in action!!
I personally think you will be fine with a cane.
The physical museum is not that expansive. Depending on your level of mobility with a cane you should be able to navigate the museum without to much difficulty. There are no stairs. The grounds are a different. They are far more expansive and require a lot more walking on varying types of ground including rock, pavement, dirt, grass, planks, wood chips, etc.
Possible, not advised, but very possible.
Since the museum also have sites of interest around the main building, walking is a must to get around. A cane should be fine to use, however, a walker will be more problematic.
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