The northwest shore of Oahu is famous for its huge winter surf. I remember hearing about the Banzai Pipeline and Waimea Bay when I was a kid, probably on Wide World of Sports on a Saturday afternoon (probably not the same Saturday afternoon I saw Endless Summer). It's pretty neat to see the real places, even if today's waves are pretty tame (they're the result of easterly trade winds wrapping around the north end of the island - whereas the winter surf is generated by swells thrown off by North Pacific storms). The waves may not have been huge, but the shore break looked brutal enough in a couple of places I worried a little bit about some of the kids. And I know those guys offshore are only a few feet of water way from a jagged bottom. Last day - time to go back to North America.
This is a wonderful small pocket beach near the northern tip of Oahu. It is bracketed by two narrow tongues of old coral that project seaward and is sheltered from the North Pacific swell by the modern reef offshore. The beach lies in the afternoon shadow of a large resort hotel perched on one of the points, but like all Hawaii beaches, it remains publicly accessible.
The old coral is reportedly 125,000 years old, dating to the last high stand of sea level, several meters above what it is today ... about what it will be in 200 years if Greenland continues to melt at the rate it is today?
In 1946, an earthquake in the Aleutians sent a tsunami southward - six hours later Hilo, on the big island, was devastated. Here near Kahuku Point, it washed inland as much as a mile and may have been 20-30' deep. This hotel, built in the 1970s, was designed with tsunamis in mind, although we probably know far more about them now than we did then. The hotel might survive, but the restaurants and the condos might not and the cars in the parking lots would probably wind up draped from trees around the golf courses.
Hanamau is a large pocket beach in a breached volcanic crater. Somehow it manages to live up to its status as a natural preserve, while also preserving the ability of millions of people every year to visit (mainly to snorkel). That the reef actually manages to survive with all that human traffic is remarkable. They do require visitors to attend a short "do not touch" video before heading down to the beach - an obligation many were trying desperately to bypass.
Most of my entries are about little gravel beaches on Puget Sound without much of a reputation -- so it's fun to add a truly famous one.
Waikiki isn't quite the uniform beach strip I had imagined. It's a strange mix of beach, groins, breakwaters, and seawalls. It's actually a series of beaches, each with its own geologic character (and probably social character, too). Gray's Beach, from the Sheraton west to Fort DeRussy, isn't much of a beach at all these days - just an undermined seawall.
Waikiki was originally a narrow barrier separating a large marshy area from the ocean, but clever humans drained the swamp, raised the land, and added sand to the beach, converting a local beach into one of the most famous coastal resorts in the world. And creating a lot of land on which to build big hotels.
Sand on Waikiki (there's not really that much of it - the nearshore is mainly a broad reef, with just a fringe of sand at the shore) has been replenished from offshore, from beaches elsewhere on the islands, and even from California. In the 1920s, the developers of Manhattan Beach (Los Angeles) found their large dunes inconvenient, so they barged them to Honolulu (really, at least it says so on the internet,. It was done by a construction firm run by the Kuhn Brothers). The beach sand is gradually being lost offshore, filling in holes and channels in the reef, and moves are afoot to pump some of it back onshore. I wonder how much sand is lost each year by tourists tracking it back to their hotels.
