There are definitely rock beaches and you can for sure swim in some areas.
The water was quite swift flowing auth whirlpools where the rivers met. I would be wary. I'm sure there are spots where it is ok.
Yes.. small river type beaches. I swim here
Jaylon Skaggs is correct that the beaches or river banks are loose rock but will allow swimming in some areas though there is a strong whirl pool at the confluence of the rivers.
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