Very interesting trip report. Even tough you didn't see or do most of the things others do you still managed to have an amazing time. Kudos for that and standing up to that level.
If you think about it, what you basically did was take nice drives, see beautiful scenery, and go some great hikes. Most people looking to do that would go somewhere like Colorado or the Southwest. I would think that to schlep to Hawaii for that would be a waste, but if you were happy with that descision, who am I to judge
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That being said, with enough research one could do all the typical Hawaiian activities such as swimming and snorkeling while still maintaining that level of tznius. As Dan mentioned, there are plenty of private beaches to be found throughout the islands; there are also many vacation rentals with private pools. Of course with a baby in tow some of those may not be practical, but there are still options.
ETA: Just saw your last post. Looks like we're on the same page
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