Scalloped Hammerhead Sharks
Scalloped Hammerheads are found through out the entirety of the eastern US waters of the Atlantic Ocean, as well as the entirely of the Caribbean. Scalloped Hammerheads are also found throughout the Hawaiian Islands. Oddly, they are not found on the Pacific coast of the USA, one of the few places in the world that they are absent.
Let me compare Molokai vs. Molokini. Molokini is a visually spectacular dive with lots of reef fish, near 100% coral cover in places and as a result, probably the quintessential dive if you are on Maui. It is also fairly benign with visitors ranging in skill level from snorkelers with lifejackets to fairly advanced divers drift diving the back wall. By contrast, Molokai is all about hammerhead sharks. You might also see tuna, dolphins, and galapagos sharks, but the hammerheads are the star attraction. It is also an advanced dive. You will be dropped off effectively in the middle of the Pailolo Channel which, even on a nice day, is much rougher than most days at Molokini. The ride to and from Molokai generates a lot of lost lunches.
Molokai is a high energy dive with a live drop off (moving boat) and lively pickup. Getting there means chopping through a channel that turns the residual sea state up to eleven. It isn't like you are diving in a bay or some protected area, that same magnified chop that turned everyone green on the bounce out is what you jump into. The first tie I dived it there was a hell of a current, the second time not so much. You drift along staring out into the blue and scanning the bottom from ~80 feet, then follow the action from there. And don't touch the unexploded ordinances on the bottom (not kidding-there are bombs down there). It is a heck of an experience and I highly recommend it-if you are up for it. It is the best place to see Hammerheads. -- Michael Kazma
Another thing with Molokai is there's a chance you may not see anything. Sure, the same is true for pretty much whenever you get in the water, but at least for Molokini, there's still coral/etc to look at. From what I remember, the Molokai site (for hammerheads) is primarily a sandy bottom. I got skunked there last time (which is why I mention it), though there was a pod of dolphins jumping around us while waiting on the surface for the boat. A previous trip, we did see a dozen or so hammerheads. --- BSOD
Molokai is your best chance to dive with Hawaii's pelagics such as schooling hammerhead sharks, large barracuda, and schools of jacks. This is one of our more advanced dives, blue water descents from a live boat and often times rough seas can make for an adventure you'll never forget. Lahaina Divers
Lahaina Divers, which offers daily advanced and beginner dive trips, can take you to Molokini Crater, or to Molokai, where hammerhead sharks abound. Some dive shops (the ones selling boat trips) will tell you that there are no good shore dives on Maui. Don't believe them! Fedor's
Fish Rain is the top dive site for hammerhead sharks. Fish Rain Review
Layang Layang Island, Malaysia
It is a long way away, and takes a lot of planning to get to, but Layang Layang Island is an island world renown for its large numbers of schooling scalloped hammerhead sharks. Layang Layang is small coral atoll in the South China Sea, off the coast of Malaysia. Numbers are very limited due to the low availability of flights, which only operate once a day a few days a week from Kota Kinabalu. So if you want to share in this breathtaking wonder, I suggest you plan your trip well in advance. There is only one dive resort on the island: Layang Layang Island Resort.
Easily the biggest drawcard for Layang Layang is the world famous and enthralling encounters with schools of scalloped hammerhead sharks, which occur frequently in its surrounding waters. It is one of the great sites to see Hammerheads. Being lucky enough to watch a big school of hammerheads glide by is an experience that will live with you for a very long time, and makes the whole journey worthwhile.
Other Great Dive Sites
According to Dive the World, the best places to find scalloped hammerhead sharks include: Cocos Island off of Costa Rica, Madivaru Corner in the Maldives, the Galapagos Islands, Komodo National Park in Indonesia, and the coast of Malaysian Borneo. The coast of Malaysia features oceanic islands and deep water atolls, the most well known of which is Layang Layang, and is among the best locations for sightings of hammerheads. All of these dive sites are in an area which features nutrient-rich deep sea upwellings, and thus bring scalloped hammerhead shark as a regular visitor. See Dive The World.