"Alright, boys. Today we will be having a day of lessons. I know it's not what-"
"I'm not sticking around for this!" Ace made to storm off, but Naia caught him by the shoulder.
"You will be staying for this one. I have allowed you to have the freedom to pick and choose when you stay, but you will not have that luxury today," Naia said harshly. "If you wish to sail on your own, you will need to know how to first."
"Who told you that?" Ace stared accusingly at Luffy.
"No one had to." Naia cuffed him on the back of the head. "You have the look in your eye. The sea calls to you. It is not uncommon."
"Fine," Ace huffed, crossing his arms.
"We'll have it on the beach today. We will be learning how to read water, specifically the ocean's water," Naia explained as they made their way down to the port. "This can help with Navigation as well as steering a ship."
"Water? We're going to read water?" Ace glared at her. "Why must you make us learn such useless things."
"Only you can decide whether or not the information is useless. I find that ocean currents tend to be very helpful."
"You need to learn them if you are to go to Fishman Island! Currents work like wind there!" Luffy exclaimed.
"Fishman Island?"
"It is an underwater island made by the Fishman. It's a beautiful place, but we won't spoil anything for you." Naia winked at the boy. "Luffy, you won't be able to do some of these exercises, but you will at least know the theories."
"Why won't he be able to do them?"
"I ate a devil fruit! I'm a rubber boy now!" Luffy stretched his face for emphasis.
"Rubber? What a stupid power!"
"It's not stupid!
"Is too!"
"Is not!"
"Is too!"
"Is not!" Naia groaned as they continued to argue.
"Boys! Enough!" Naia pushed the boys apart. "I will not tolerate your fighting today, and Ace, if that attitude stays, you will never make it out of the East Blue. A captain must have a collected mind who thinks of the journey ahead and his crew not only of himself."
Ace glared at her but remained silent.
"Good, now we shall begin with the basics." Naia gestured for them to sit while she stood in the shallow waters with the waves batting at her feet. "There are two separate forces that move the ocean."
"Tides and currents!" Luffy exclaimed.
"Very good. Do you know what the difference between the two is?"
"Aren't they the same?" Ace huffed.
"Yes and no, tides are most commonly found near the coast or on a beach while currents involve the open ocean," Naia explained. "A simple way to remember it by is that tides go up and down while currents go back and forth. The tide impacts the ocean's currents along with the wind, shape of the land, and the temperature of the water."
"So depending on how the tide crashes onto land, it will determine the state of the current?" Ace asked.
"Yes, Ace, that is correct." Naia smiled at the boy, who flushed under her praise. "To correctly judge the tide and current takes years to master, but you have to start somewhere. The first is to know the speed and direction. Ace, come here." Naia led the boy out to about knee-deep water for her and waist-deep for him. She lightly grasped his hand before putting it just under the water. His eyes went large as the water brushed against his hand with an invisible force.
"Is that the current?" Ace asked, his eyes full of wonder.
"You tell me. Which direction is it going?"
"It's… it's moving forward."
"Very good, and if you move your hand a little this way." The boy's eyes glistened with interest as the direction changed, flowing up and down his arm. "The ocean is very much alive and teems with all sorts of life and energy."
"I wanna feel!" Luffy launched himself over to them, only to kneel over as soon as the water made contact with his body. Naia swept him up into her arms before he could fall completely under.
"Lu! That was very dangerous!" Naia scolded.
"Shishishi, I knew you would be there to catch me!" Luffy grinned. Naia shook her head but continued with her lesson. Ace slowly became more and more invested in learning how to read the water. Its uses, why it was needed, and how to use it to their advantage. Naia looked up every once in a while to see a few pirates sitting just close enough to hear but not enough to draw attention to themselves. She even saw Shanks loitering about up on the dock listening to her descriptions of the ocean's water.
"ACE? Ace, are you over here?" A young voice shouted. Naia paused her explanation as a young blond boy burst out onto the beach. Ace jumped up, his eyes darting to her and then back to his blond friend.
"He is more than welcome to join us, Ace." Naia shifted her attention to the boy running up to them, waving frantically.
"Let him join, Ace!" Luffy shouted, his grin never leaving his face.
"He's my friend, and we don't need anyone else!" Ace took off toward his friend. The two argued for a moment, with Sabo glancing at them from time to time. Luffy waved at him every time he did, and Naia joined at the boy's insistence. Sabo smiled at them before turning back to Ace, glaring.
"Hi! I'm Sabo, and you don't look anything like the gremlin and troll Ace describes you as!" Naia felt her face fall at the comment. A troll?
"Hey! She's not a troll, and I'm not a gremlin!" Luffy glared at the older boy. "That's a mean thing to say! 'Pologize now!"
"Sorry, sorry," Sabo recited, not looking the least bit sorry. Naia rolled her eyes at the blatant display of disrespect.
"We are learning about ocean currents. Would you like to join us?" Naia asked.
"Ocean currents? Like to navigate?" Sabo's eyes grew wide with curiosity and excitement.
"Exactly that." Naia smiled softly at the boy. When she had met him the first time, he was much older, but his passion for navigation never dulled. Ace grabbed the boy's shoulders, and the two began to whisper insistently at each other. Sabo looked like he wanted to stay while Ace was frantically pointing towards the jungle. Unfortunately, it seemed Ace won the argument, and the two took off into the jungle. Naia sighed in defeat as Luffy shot after them not a moment later. So much for mandatory lessons.
"Be back by dinner! Sabo is welcome to join us!" Naia shouted after them.
"Looks like you've been ditched," Shanks' amused voice chortled. Naia glared at the man.
"Those boys will be the death of me. Between the fighting and disappearing," Naia huffed as she sat down in the sand. The ocean lapped at her toes as she pouted.
"Why don't you show me what it was that was making Ace so inspired?" Shanks suggested, rubbing his neck sheepishly.
"The current? Haven't you already felt it, Mr. Pirate Captain?" Naia brushed the sand from her shorts as she started to head back to the village. "I don't need pity, Red."
"I'm not pitying anyone, least of all you. Now, come. Show me." Shanks tugged her arm sharply, causing her to stumble back toward him.
"Fine, but it's not anything magical to someone who has experienced the ocean before," Naia grumbled.
"Dahahaha, have some confidence in yourself!" Naia rolled her eyes but led the pirate out to the water. They waded further out until they were both waist-deep.
"Put your hand just here. Loosen your muscles and let it float in the water," Naia instructed as she guided his hand just below the surface. Naia smiled when Shanks' eyes widened in recognition.
"Naia, I know of the current. Have even been dragged down by it, but this feels different. More alive than what I have come to know."
"Of course, the ocean is alive," Naia giggled as the man wiggled his fingers through the water. "It's constantly teeming with energy."
"Dahahaha, I could've told you that." Shanks grinned widely.
"Oh?" Naia let a sly smirk slide over her face. "What else could you teach me?"
"There are currents on the Grandline that are unlike anything else in the world!" Shanks boasted, "And I happened to have ridden one, in particular, many times."
"Do tell," Naia purred. The water danced around them as they waded in the shallows. Naia brushed her hair back, letting her hand trail down her long curls that pooled at her chest. Her smile grew as she watched his eyes follow her hand.
"W-well, there is a rare current known as a Knock-up Stream," Shanks stammered, a slight flush on his cheeks as his eyes remained glued to her hand that was twirling her hair. "It shoots straight into the sky!"
"Oh?" Naia tilted her head in interest, cupping her hands under the water. "Like this?"
"Hey!" Shanks sputtered as a small stream of water hit him in the face. Naia giggled as she watched the pirate captain wipe his face.
"Or was it like this?" She sent a wave of water over him. Shanks ducked under the water to dodge and went to send out his own attack, but Naia was already gone. Her giggles echoed behind him.
"How did you get over there so fast?"
"If I told you, I would have to kill you," Naia stated, an evil smirk crossing her face.
Shanks blinked at her as she retreated to the beach. The water swirled around her, letting her escape with ease.
"What does that mean?" Shanks waded after her, trying to catch up. "What do you mean? Naia!"
Naia laughed as the man attempted to catch up to her. She waved at Benn and Makino as she raced by. Makino had a conflicted look on her face as Shanks followed not long after, but Naia didn't let herself dwell on it. This was too much fun.
Want to learn more about tides? Naia's information comes from years of experience and this website here!
.gov/navigation/tidesandcurrents/