"A shipwreck?" Law paused.
"That's what the bird chick said, Captain," Shachi shrugged.
"It might have been recent if it hasn't sunk yet," Robin reasoned. "Perhaps there are survivors?"
Law took off his hat and scratched his head. "Damn it. Let's go check it out."
Although he was a pirate, he was also a doctor. It was difficult for him to simply abandon potential patients. He could do it if he had to choose between saving strangers or saving his own crew, but there wasn't any evidence that they actually were in any danger. It was largely just a gut instinct that told him that he ought to get out of dodge.
Kicking the engine into gear, the Polar Tang trundled along according to the directions of Cabernet who once again took to the air to guide them to the wreck.
Before long, the submarine was bumping into bits of shattered wood.
"Most of these pieces are very small," Franky said, scooping a bit of wood from the water. "Not even a sea king chewing up a ship would reduce it to… well, smithereens."
"What in the world could do it then?" Usopp shuddered, not wanting to imagine what fate befell this ship.
"A buster call's worth of cannon fire, maybe," Franky answered seriously. "The only way this could happen is with a deliberate and concerted effort, or enough force to level a mountain. As you might imagine, the latter isn't very likely."
"A giant, perhaps?" Usopp suggested. Brogy and Dory came to mind.
The conversation tailed off and soon the main wreckage could be seen. There wasn't much left to be seen, however. A big broken piece of what was once the stern of a ship was in the process of sinking whilst the sea around it looked to be filled with mulch and a few scattered planks that survived.
"Keep an eye out for survivors," Law ordered.
"I don't know if we'll find any," Usopp said as he bit his nails. "I don't even see any dead out there."
That was an unnerving thought for everyone.
"Perhaps they escaped the vessel before this happened? We wouldn't know if the lifeboats were taken or not in this mess," Robin gave them some hope.
"I see someone!" Cabernet shouted from above.
She quickly flew over behind the sinking stern. She emerged shortly after pulling a barrel through the littered water with a man clinging onto it for dear life.
Law didn't need to tell his crew what to do. They were well trained in how to help him with patients, so they fished the man out of the water as delicately as they were able and gently laid him onto the deck of the Polar Tang.
The man looked old, but his dark graying hair and beard suggested he was only a rough late fifties in age. His right leg was missing below the knee, a recent injury judging from the blood staining the torn pant leg and the belt that was pulled tight to stop it from bleeding any more than it already has.
Law made sure the man was still breathing before making sure the leg was stable enough to move him to his operating room. Law gave a quick nod and his crew moved in with a stretcher, transferring the man with practiced ease and bringing inside the ship.
When Law was gone, Zoro spoke up. "That man has a strong will to live."
"Because of the leg?" Usopp asked the obvious.
"Not just that. He threw himself overboard with that barrel," Zoro corrected.
"How do you know that?" Usopp asked, somewhat disbelieving.
"The barrel was intact," Franky explained. "Do you see any other barrels out there?"
Usopp looked around just to make sure, but his own memory didn't fail him. There really weren't any other barrels floating in the wreckage.
"I didn't see any more, either," Cabernet added, further cementing the truth.
…
It was a couple of hours before Law came out of his operating room. With his devil fruit power, the severed leg wouldn't take that long, but he went ahead and did a full check up on the man to make sure he was in good health.
Thankfully the man didn't have a rare blood type or anything, so his blood loss wasn't too big of an issue.
"How's he looking?" Franky asked.
"He isn't in danger. I'm going to let him rest a bit before I wake him up," Law said.
"Why wake him up?" Usopp asked. "He's been through quite a lot…"
"Because we need answers. These waters are strange, and I want to know why. Perhaps his little accident will shed some light on the mystery," Law spoke. "In the meantime, we're getting far away from this place as fast as we can."
"Are we in danger?" Kin'emon came from below decks with Kanjuro and Momonosuke.
"Maybe, maybe not. I'd rather not find out the hard way," Law huffed, getting tired of explaining himself.
"Captain! Something is coming straight for us, and fast!" one of the Heart crew shouted in an urgent tone. He manned a station that the present Straw Hats had been told was called a 'sonar system'.
"What is it?!" Law shouted back.
"I- I don't know, but it's huge!" the man fiddled with the instruments in front of him futilely. A blip on the screen got closer and closer to the center, beeping louder and faster as it went.
The Polar Tang lurched as if it was bowled over by a tidal wave. Except that they were currently underwater by quite a ways, so that wasn't possible.
Everyone scrambled to grab hold of something or failed to do so and toppled over. When things finally came to rest, everyone got to their feet and many eyes shot warily at the sonar screen.
*BEEP Beep Beep beep beep beep*
The unknown blip kept moving away, seemingly unaware or uninterested in the submarine.
"Was that a sea king?" Law asked.
"I've never seen a sea king that fast before, captain," the crewman stated. "I don't know if even mermaids can swim that fast…"
It was widely known, or at least believed, that mermaids were the fastest swimmers in all the seas. The thought of a sea king moving faster than that was terrifying.
"Maybe it was another submarine?" Usopp offered.
"I think I'd rather it be Davy Jones himself than a submarine of that size. The technology necessary to propel that much mass through water would be well beyond us," Law said.
"Would a vessel that big possess enough firepower to obliterate a ship, though?" Robin added her own two cents.
"Shush, you!" Usopp begged.
"Oh?" Franky's mouth widened into a smile. "I hope it is a ship! Imagine what a beauty she'd be!"
"You can chase after your own death when you're not on my ship anymore. We're leaving," Law put his foot down. Franky leapt to the floor and pleaded at his feet to change his mind.
Fortunately for everyone else, Law wasn't having any of Franky's nonsense. "Get a move on!"
The Heart pirates scrambled to follow their captain's orders. It was clear that he was in no mood to tempt fate any further, and they weren't about to argue with him about it.