|“You're the Master of Water. There's no one more connected to the sea than you.”|
|— Jay to Nya in "Unsinkable"|
The 2021 season of LEGO Ninjago, subtitled Seabound, is preceded by The Island. It aired in April 2021, the same year as the series' 10th anniversary. Nya is the focus character, Kalmaar serves as the main antagonist, and the Merlopians serve as the villainous faction of the season.
When Nya’s powers are disrupted, the ninjas set off in search of answers and find themselves at the bottom of endless oceans where they discover that her powers are linked to an ancient mythical creature.
- Benthomaar - Cole Howard
- Child - Erin Mathews
- Cole - Kirby Morrow
- Glutinous - Sam Vincent
- Gripe - Brian Drummond
- Henchman - Paul Dobson
- Jay - Michael Adamthwaite
- Kai - Vincent Tong
- Kalmaar - Giles Panton
- Lloyd Garmadon - Sam Vincent
- Maya - Jillian Michaels
- Misako - Kathleen Barr
- Miss Demeanor - Erin Mathews
- Nya - Kelly Metzger
- P.I.X.A.L. - Jennifer Hayward
- Ray - Vincent Tong
- Samurai X Mech - Kelly Metzger
- Trimaar - Ron Halder
- Wu - Paul Dobson
- Zane - Brent Miller
|Season Ep #||Series Ep #||Image||Episode name||Airdate|
|1||165||"A Big Splash"||April 4, 2021 (Canada)|
|2||166||"The Call of the Deep"||April 4, 2021 (Canada)|
|3||167||"Unsinkable"||April 11, 2021 (Canada)|
|4||168||"Five Thousand Fathoms Down"||April 11, 2021 (Canada)|
|5||169||"The Wrath of Kalmaar"||April 18, 2021 (Canada)|
|6||170||"Long Live the King"||April 18, 2021 (Canada)|
|7||171||"The Escape from Merlopia"||April 25, 2021 (Canada)|
|8||172||"The Tale of Benthomaar"||April 25, 2021 (Canada)|
|9||173||"The Storm Amulet"||April 27, 2021 (UK)|
|10||174||"Riddle of the Sphinx"||April 27, 2021 (UK)|
|11||175||"Papergirl"||April 28, 2021 (UK)|
|12||176||"Master of the Sea"||April 28, 2021 (UK)|
|13||177||"The Calm Before the Storm"||April 29, 2021 (UK)|
|14||178||"Assault on Ninjago City"||April 29, 2021 (UK)|
|15||179||"Nyad"||April 30, 2021 (UK)|
|16||180||"The Turn of the Tide"||April 30, 2021 (UK)|
- 71750 Lloyd's Hydro Mech
- 71752 Ninja Sub Speeder
- 71754 Water Dragon
- 71755 Temple of Endless Sea
- 71756 Hydro Bounty
- This season's name, Seabound, sounds very similar to the name of Season 6, Skybound. Nya is one of the main focus characters in both seasons.
- Although Kirby Morrow unexpectedly passed away in November 18, 2020, he recorded Cole's lines for this season prior to his death. LEGO announced that the 2021 episodes will be dedicated to his honor.
- According to Tommy Andreasen:
- On January 14, 2021, the Ninjago's 10th anniversary, he said that they had received the render of the last episode of 2021 from WildBrain, and had done the first voice record for the 2022 episodes the day before.
- Depending on how this season turns out, it may be his favourite.
- In response to a fan wanting "Nya angst," he stated, "We shall provide!".
- There will be a "new actor... new character. And easily one of the weirdest and wonderful ones we have ever come up with."
- A future season will go down as the best in the series' history.
- Nya would face "her biggest challenge yet later this year."
- He tweeted "Reviewing final sound mix and color grading on the last of the 2021 episodes today. It is not an easy watch for several reasons..."
- When asked if Cole will be retired from the show following the season's conclusion, Tommy replied that they "have considered every possibility and it was not a task we took lightly."
- There will be more focus on Jay and Nya's relationship than there is in most other years.
- According to Bragi Schut, "[t]here are tons of fun things coming, and we're all hard at work on Ninjago."
- Tommy Andreasen has also asked, "What do you hope for… a happy satisfying ending to the  episodes? Or a chilling heartbreaking endings to the episodes?"
- This is the first season since Hunted and the first WildBrain season where Jillian Michaels is part of the voice cast.
- Amount of times a different character reads a title card:
- This is the first season which was released earlier than the sets.
- This is the first WildBrain season to feature death.
- https://youtube.com?watch=NsRKL38dQ7o&t=7176 (live-chat)