Question for why certain things are different in French Polynesia.

My kids flew back to North America with some very beautiful photos of the islands around Tahiti. The sand beneath the shore waves are very sharp mounds where Stingrays and sharks live and it is always suggested that the swimmers wear water shoes or fins. I have surfed all over the Hawaiian Islands and never nurt my feet.
Are the Hawaiian islands older than the French Polynesia islands and would therefore be more worn down? In the Hawaaian islands the sand along the big island is very sharp but that island is still spewing lava.

The oldest island in the Hawaiian chain is 5.1 million ya while Tahiti is ca 1.7 million ya. Both are volcanic chains. the Hawaiian chain is much older than the double volcanos of Taihiti, home of the modern tatoo.
Cap’t Jack

Sandy we went surfing on both Maui and Oahu 2 years ago and I can tell you from painful experience that both islands have some pretty sharp coral on many of the beaches. I ran into the water on Waikiki beach the first day on Oahu and sliced my feet up pretty well.

There is an excellent book (so I was told as I haven’t read it yet) where I am sure you can find your answer, Sandy. It’s called “The World’s Beaches: A Global Guide to the Science of the Shoreline” by Orrin H. Pilkey, William J. Neal and James Andrew Graham Cooper. I have had it on my list for a while but never got to it.

We spent a couple of weeks on Kauai and the beaches were wonderful, not unlike my youth in Malibu. I grew up barefoot. Even today, I wear shoes only to drive. I’m third generation Santa Monica.

I dont doubt that there are some soft coral free beaches on some of the islands. My only point is that not all ( and perhaps not even most) beaches on the hawaiian islands are like that.