The two men went out of the captain's cabin and towards the railing. Edward turned his back to the Ocean and spread his arms, then just let himself fall backwards into the water. Just a new way of doing that. And quite refreshing.

"Get ready, Mister Kenway!", Jacob took a running jump and pulled off a dive-bomb, making the biggest splash around the area. It made a big wave, also burying Edward underneath.

Edward flinched and thought he had to cough out some water he might have swallowed accidentally, but it was not as usual. It didn't even bother him. He shook his head to get rid of the confusion. "You think that was a wave? I show you how it's done!"
He splashed Jacob, who just laughed and then playfully attacked Edward and messed up his hair. "Haha, you got a nest on your head. Take this.", he splashed him once again.

"Bold of you to attack me in my element.", Edward used the water to elevate Jacob and toss him several feet away.
"Woah! Edwaaaaard!", Jacob quickly swam back to Edward. He had cooled off. "Hey, actually we could be trying to see now if you could breathe under water. I'm here, nothing will happen to you."
"Hmm.. Aye, maybe if you would turn into a whale, you could support me? In case I choke, I have something to hold on.", he could stay on Jacobs back in that way.
"Let's do that.", Jacob swam a bit away to then turn into that large beast. He waited for Edward and adjusted his position towards the ship slightly.

Edward swam towards the now very large Jacob and picked a spot which was okay. He took note that this kind of whale had a very small dorsal fin but very large pectoral fins. Back to the diving. Edward felt that he got distracted easily those days. But now he dipped his head under water. Yes, no sane person would now take a breath. But he did risk it. And it worked. He swam from Jacob's back and further down to the eye. He could swim normally and ... breathe. It felt different. Maybe as if the water was suddenly like real dense air. But it worked.
"It works.", he told Jacob once he was up to the eye.

When Jacob saw Edward, he found him nearly cute. So small! He replied to Edward with a cheerful whale song. Then he took in some air and started to swim further down. Maybe Edward would come along. Hopefully.

Edward quickly swam and grabbed Jacob's pectoral fin. Yes, deep diving. Why not? And even while now he could breathe under water he could not swim as fast as Jacob with his mighty fins.
He remembered how in his younger days in the Caribbean sea, he had used a bell to dive deep like this. Soon enough even the faint moonlight disappeared and the two of them swam in eternal darkness.

Edward still made out an Oarfish passing by, hanging in the Ocean like a lonely needle. There was some kind of bioluminescence to it. He also spotted other fish, mostly thanks to them basically glowing in the dark. He wondered just how deep this would go. He felt safe thanks to Jacob being such a big and friendly whale.
What Edward didn't know was that down in the deep, the pressure increased immense and would have crushed him if the Trident of eden would not have prevented that. Right now he was challenging the Trident and it showed by thin geometric lines starting to cover Edward's body.

Jacob also noticed how the water turned so much colder. He also saw the glowing creatures and they kind of scared him. Some of them looked really dangerous, yet fascinating. And this kind of stuff was living here? Why id these animals glow? Was that electricity? He tried not to come too close to them.

Edward could hear an array of sounds. He believed to hear what these animals were saying. And it sounded so bizarre! There was the cacophony of the same word repeated over and over. Some sounded frightened. And in the distance, whales sang beautiful songs of older times. Then he could hear something approaching them.
"Jacob, watch out!"

It was a Giant Squid. Sperm whales usually had no problem fighting critters like this, but could Jacob take it on? His teeth were not even hard!

Jacob had been so fascinated by it all that Edward's warning had come too late and suddenly it was right there. He thought of swimming away, but already tentacles were grabbing at him and there was something sharp among them!
Jacob cried out in pain and hoped that the other whales may hear him.

Edward noticed his warning had been too late. Jacob's cries for help made him feel agitated and so he summoned his Trident. "Get lost!", he swam to get ready and stab the Squid, but the Squid already let go of Jacob and swam off, blubbering some kind of apology.

"Are you alright? Let's get back up.", Edward swam around Jacob to see if he was wounded too badly. But it seemed alright. He held onto Jacob's pectoral fin once again.

Jacob was glad when the Squid was gone and when he felt Edward on his fin, he swam back to the surface.
He turned back to his human shape and moved up on the ship. His back was riddled with bloody streaks from the fight. They were burning from the salty water. "Ouch. My, what a beast. Good thing you intervened."

Edward came back on board after Jacob. The geometric lines on his body were gone again. He gave Jacob's back a concerned look and got some water and the first aid kit ready to take care of him. Jacob sat down to let Edward do that unpleasant work. "I should have intervened earlier."
"I'm fine, really.", but Jacob hissed, when Edward cleaned and dressed the wound.
"Aye, A can see that.", Edward rolled his eyes. Luckily, the wounds seemed to at least have shrunken as well when Jacob had turned from whale to human.
"But did you see what was down there? All those glowing fishes. You don't get to see that every day."

"I don't think we'll be going down there again. There are nicer places below sea level. Like coral reefs.", Edward could imagine a nice trip to the colourful reef banks near Australia. Or diving in the Red Sea.
Jacob yawned and got up when Edward was done. "Thanks. .. man, I would really be fucked if you weren't there. But now I'd rather want to go to sleep."
"Aye, I could use some sleep."

They went below deck and put on at least some pants. Edward saw the bottle of oil next to the bed and blushed as he remembered what they had done not too long ago. He took the bottle and put it back into the pantry.
Then Edward came back and joined Jacob in bed. It was nice and cosy. "Good night."
Jacob smiled softly. "Good night, Ed."

_

Alright.
And this is the point where I think I will end this fanfiction.
If you made it this far, congratulations and thank you so much for making it through to here.
I might write more fanfictions when I will feel inspired but for now I will let it rest.