Fortunately, the bombs turn out to be no danger at all. A Navy team disarms a bomb that looks menacing, and later I learn from the archives that the bombs carried by Saratoga were filled with plaster, not explosives. If marine growth and corrosion had not covered the bombs, we might have seen the stenciled message that I find on the photos of the tests — rows of big bombs marked “INERT.” But the sharks can be aggressive, as we discover when we get too close. They are not “Jaws” size, but they can still tear out a big chunk of flesh, so we usually avoid them. One day, a shark gets too close, but I lash out and punch him in the gills, a sensitive spot. It hurts and he backs off — as do I. Another time, a shark swims by and rips into a fish, tearing it in two. He glares at me, half a fish dangling from his mouth, as if he’s daring me to try and take it. “No, go ahead,” I mumble in my regulator. “It’s your fish.”

The only other close call on Saratoga comes years later, on a dive with Fabio Amaral, as we probe a passageway inside the wreck during a Discovery Channel filming expedition. Dropping down Saratoga’s small bomb elevator, we make our way to a hatch that we are able to squeeze through, into a long corridor running off into the darkness. Fabio has been here before and laid down a line to guide us back should the silt stir up. We follow the line to deep inside Saratoga. More than halfway down, we stop in alarm at the sound of a loud bang behind us. When I look back, my lights pick up a wall of silt racing towards us. Fabio and I grab each other by the shoulder and go mask to mask as the silt washes over us, blacking out the corridor. The powerful glow of our lights is useless in the turbid, muddy water. Holding my light up to my face, I can just make out Fabio’s eyes, wide open and doubtless a mirror of my own fear. Dive training takes over, though, and we grope for the line. Slowly tracing it with our fingers, we move back until we reach a mass of fallen rusty steel. The deck above us has collapsed, burying the line and probably trapping us inside the sunken ship.

Then we both get an inspiration. The deck above us has fallen down, but that means another corridor has opened up. We slowly rise up out of the cloudy silt and find ourselves in a murky but clearer passageway. Following it, we come up to a sealed hatch that must lead into the bomb elevator. Straining against rusty hinges, we push it open to find ourselves floating above a mess of bombs at the bottom of the elevator. After a “thumbs up” sign, we swim straight up and out, breathing a sigh of relief.

The thrills of a close escape, however, do not compare with the emotional impact of looking at these historic ships and the dramatic damage wrought by the atomic bomb. Saratoga has a huge dent in the flight deck caused by the falling column of water and silt thrown out of the lagoon by the bomb. It’s just one dent, but it’s a big one: 230 feet long, 70 feet wide and 20 feet deep. It looks like Godzilla stomped on the flight deck. The battleship Arkansas, a quarter mile away, is in even worse shape. The armored hull is upside down, warped and smashed nearly flat. A hundred feet of superstructure, masts and turrets lie buried in the coral sand, with only several feet of clearance between the main deck and the seabed. The force of the blast flipped and smashed Arkansas, then hammered her down with such violence that she is nearly one with the bottom of the lagoon. The attack transport Gilliam is something else altogether. Caught in an atomic fireball and swept by extreme temperatures equal to those on the surface of the sun, the ship has partially melted. It looks like a child’s plastic toy left out on a hot sidewalk, thick steel drooping and deformed. A bulldozer from the ship’s deck, tossed off by the blast, lies nearby with its thick blade twisted into an “S” by the heat.

On our first dive on the massive Japanese battleship Nagato, Lenihan, Nordby, Murphy, Livingston and I realize that we’re the first to visit her since the 1940s. We swim around the stern, past the huge bronze propellers that are surrounded by a swarm of sharks. Dan Lenihan and I drop down to the seabed and slip under the overhang of the stern to make our way in the gloom towards the barrels of the aft gun turret. As we hover in front of the gun muzzles, we both think of our dives at Pearl Harbor. Japanese ordnance experts modified some of the 16-inch shells from Nagato’s magazines into the aerial bombs dropped at Pearl. One of the bombs punched through Arizona’s decks and set off the magazine explosions that destroyed her. I can’t help think that this is a full circle for us, particularly Dan, who has worked very hard to document Arizona and bring more of her story to the public.

That full circle feeling comes back on a later dive that we start aft from Nagato’s bow. As I slip out from under the deck, my eyes catch something ahead in the gloom. Dan and Murphy also see it, and we all swim forward at a fast clip. The entire superstructure of the ship, instead of being crushed like that of Arkansas, is laid out on the white sand. It’s the bridge; it’s the bridge of Nagato, where Admiral Yamamoto heard the radio message that the attack on Pearl Harbor was successful: “Torn, tora, torn!” It’s incredible. Sometimes, science be damned, you just get excited by what you find.

My last dive at Bikini Atoll takes place a decade after the National Park Service survey. With John Brooks, a former NPS colleague, and Len Blix, the assistant dive master at Bikini, I drop down to look at the destroyer Anderson. (Since our 1989–90 survey, Bikini has been opened to the world as a unique dive park for those with the skill and the cash to journey to what has been called the “Mount Everest of wreck diving.”) Anderson is a famous ship that fought in many battles, screening aircraft carriers in some of the greatest sea fights of the Pacific War, including the Coral Sea and Midway. She shelled Japanese shore installations at Tarawa and survived the war only to die beneath the dragon’s breath of the atomic bomb.

Anderson lies on her side in the dark blue gloom. We approach the stern, passing over a rack of depth charges that have tumbled free and lie scattered on the sand. The decks seem undamaged, except for a torpedo-launching rack that has fallen off. The bridge lies open, its hatches blasted off. When I look down into the bridge, the dark interior swarms with hundreds of small fish that have sought shelter inside this sunken warship. Moving forward, I see a subtle reminder of the power of the atom. One of the destroyer’s 5-inch guns has been twisted by the heat of the blast so that it points straight back to the bridge.

As I sail away from Bikini for the last time, I pause to reflect on all that I’ve seen there over the years. The crushed hulls, toppled masts and abandoned test instruments are material records that preserve the shocking reality of Operation Crossroads in a way that can never fully be matched by written accounts, photographs or even films of the tests. This ghost fleet is a powerful and evocative museum in the deep. It is a very relevant museum, too. Operation Crossroads and the nuclear age that followed have had and continue to have a direct effect on the lives of every living being on the planet. The empty bunkers and the abandoned homes of the Bikinians remind us of David Bradley’s 1948 comment that the islanders might not be the last “to be left homeless and impoverished by the inexorable Bomb. They have no choice in the matter, and very little understanding of it. But in this perhaps they are not so different from us all.” As I leave Bikini, I hope that it is a record of the past and not the harbinger of a terrible future.