S04E21: Octonauts and the Kelp Monster Mystery
Dashi teams up with her little sister Koshi to help the Octonauts solve a mysterious disappearance in the Kelp Forest. This is the second episode in which is unknown who sounded the Octo-Alert.
Previous Episode 
Season 1
The Undersea Storm
S1E1 / 05 Oct 2010
The Giant Squid
S1E2 / 11 Oct 2010
The Great Algae Escape
S1E3 / 13 Oct 2010
The Walrus Chief
S1E4 / 07 Oct 2010
The Flying Fish
S1E5 / 08 Oct 2010
The Narwhal
S1E6 / 26 Oct 2010
The Monster Map
S1E7 / 19 Oct 2010
The Crab and the Urchin
S1E8 / 06 Oct 2010
The Albino Humpback Whale
S1E9 / 21 Oct 2010
The Remipedes
S1E10 / 14 Oct 2010
The Orcas
S1E11 / 12 Oct 2010
The Blobfish Brothers
S1E12 / 18 Oct 2010
The Decorator Crab
S1E13 / 05 Nov 2010
The Whale Shark
S1E14 / 04 Oct 2010
The Cookiecutter Sharks
S1E15 / 13 Dec 2010
The Jellyfish Bloom
S1E16 / 16 Dec 2010
The Speedy Sailfish
S1E17 / 15 Oct 2010
The Vampire Squid
S1E18 / 08 Dec 2010
The Humuhumunukunukuapua'a
S1E19 / 10 Feb 2011
The Giant Spider Crab
S1E20 / 11 Feb 2011
The Giant Kelp Forest
S1E21 / 22 Oct 2010
The Hermit Crabs
S1E22 / 02 Nov 2010
The Hungry Pilot Fish
S1E23 / 07 Dec 2010
The Beluga Whales
S1E24 / 06 Dec 2010
The Snot Sea Cucumber
S1E25 / 29 Oct 2010
The Giant Whirlpool
S1E26 / 01 Nov 2010
The Slime Eels
S1E27 / 26 Jan 2011
The Arctic Orcas
S1E28 / 25 Jan 2011
The Lost Sea Star
S1E29 / 20 Oct 2010
The Giant Jelly
S1E30 / 10 Dec 2010
The Snapping Shrimp
S1E31 / 28 Oct 2010
The Kelp Forest Rescue
S1E32 / 04 Nov 2010
The Enormous Elephant Seal
S1E33 / 27 Jan 2011
The Sardine School
S1E34 / 28 Jan 2011
The Eel Ordeal
S1E35 / 01 Feb 2011
The Dolphin Reef Rescue
S1E36 / 31 Jan 2011
The Pirate Parrotfish
S1E37 / 04 Feb 2011
The Electric Torpedo Rays
S1E38 / 07 Feb 2011
The Midnight Zone
S1E39 / 27 Oct 2010
The Mixed-Up Whales
S1E40 / 03 Nov 2010
The Seahorse Tale
S1E41 / 09 Dec 2010
The Enemy Anemones
S1E42 / 25 Oct 2010
The Crafty Cuttlefish
S1E43 / 08 Feb 2011
The Lost Lemon Shark
S1E44 / 09 Feb 2011
The Baby Dolphin
S1E45 / 17 Dec 2010
The Scary Spookfish
S1E46 / 24 Jan 2011
The Oarfish
S1E47 / 14 Dec 2010
The Combtooth Blenny
S1E48 / 15 Dec 2010
The Marine Iguanas
S1E49 / 02 Feb 2011
The Dwarf Lantern Shark
S1E50 / 03 Feb 2011
Season 2
The Colossal Squid
S2E1 / 19 Nov 2012
The Adelie Penguins
S2E2 / 20 Nov 2012
The Coconut Crabs
S2E3 / 21 Nov 2012
The Great White Shark
S2E4 / 22 Nov 2012
The Sea Snakes
S2E5 / 23 Nov 2012
The Bowhead Whales
S2E6 / 26 Nov 2012
The Jawfish
S2E7 / 27 Nov 2012
The Porcupine Puffer
S2E8 / 28 Nov 2012
The Damselfish
S2E9 / 29 Nov 2012
The Scared Sperm Whale
S2E10 / 30 Nov 2012
The Long Armed Squid
S2E11 / 11 Mar 2013
The Fiddler Crabs
S2E12 / 12 Mar 2013
The Manta Rays
S2E13 / 13 Mar 2013
The Swashbuckling Swordfish
S2E14 / 14 Mar 2013
The Triggerfish
S2E15 / 15 Mar 2013
The Mimic Octopus
S2E16 / 13 May 2013
The Lionfish
S2E17 / 14 May 2013
The Leafy Sea Dragons
S2E18 / 15 May 2012
The Manatees
S2E19 / 16 May 2013
The Saltwater Crocodile
S2E20 / 17 May 2013
The Humphead Parrotfish
S2E21 / 02 Sep 2013
The Gulper Eels
S2E22 / 03 Sep 2013
Season 3
The Siphonophore
S3E1 / 04 Sep 2013
The Water Bears
S3E2 / 05 Sep 2013
The Cone Snail
S3E3 / 06 Sep 2013
The Artificial Reef
S3E4 / 09 Sep 2013
The Humpback Whales
S3E5 / 10 Sep 2013
The Pelicans
S3E6 / 11 Sep 2013
The Sea Pigs
S3E7 / 12 Sep 2013
The Yeti Crab
S3E8 / 13 Sep 2013
The Barracudas
S3E9 / 10 Mar 2014
The Duck-Billed Platypus
S3E10 / 11 Mar 2014
The Sea Skaters
S3E11 / 12 Mar 2014
The Mudskippers
S3E12 / 13 Mar 2014
The Harbour Seal
S3E13 / 14 Mar 2014
The Lion's Mane Jellyfish
S3E14 / 17 Mar 2014
The Red Rock Crabs
S3E15 / 18 Mar 2014
The Sea Sponge
S3E16 / 19 Mar 2014
The Immortal Jellyfish
S3E17 / 20 Mar 2014
The Urchin Invasion
S3E18 / 21 Mar 2014
The Hammerhead Sharks
S3E19 / 21 Sep 2015
The Loggerhead Sea Turtle
S3E20 / 22 Sep 2015
Season 4
Octonauts and the Poison Dart Frogs
S4E1 / 23 Sep 2015
Octonauts and the Hidden Lake
S4E2 / 24 Sep 2015
Octonauts and the Octopod Mystery
S4E3 / 25 Sep 2015
Octonauts and the Baby Sea Turtles
S4E4 / 28 Sep 2015
Octonauts and the Walrus Pups
S4E5 / 29 Sep 2015
Octonauts and the Mantis Shrimp
S4E6 / 30 Sep 2015
Octonauts and the Loneliest Whale
S4E7 / 01 Oct 2015
Octonauts and the Tree Lobsters
S4E8 / 02 Oct 2015
Octonauts and the Convict Fish
S4E9 / 14 Dec 2015
Octonauts and the Emperor Penguins
S4E10 / 16 Dec 2015
Octonauts and the Crawfish
S4E11 / 03 Dec 2016
Octonauts and the Flamingos
S4E12 / 04 Dec 2016
Octonauts and the Tiger Shark
S4E13 / 27 May 2017
Octonauts and the Sunfish
S4E14 / 28 May 2017
Octonauts and the Coelacanth
S4E15 / 29 May 2017
Octonauts and the Surfing Snails
S4E16 / 06 Sep 2017
Octonauts and the Yellow Bellied Sea Snakes
S4E17 / 13 Sep 2017
Octonauts and the Hippos
S4E18 / 20 Sep 2017
Octonauts and Operation Cooperation
S4E19 / 27 Sep 2017
Octonauts and the Bomber Worms
S4E20 / 23 Oct 2017
Octonauts and the Kelp Monster Mystery
S4E21 / 24 Oct 2017
Octonauts and the Coconut Crisis
S4E22 / 25 Oct 2017
Octonauts and the Baby Gator
S4E23 / 26 Oct 2017
Octonauts and the Spinner Dolphins
S4E24 / 27 Oct 2017
Season 5
Bluefin Tuna
S5E2 / 27 Mar 2023
Blue Whale Rescue
S5E3 / 28 Dec 2020
Season 6
Episode 1
S6E1 / 01 Jan 2021
Episode 2
S6E2 / 08 Jan 2021
Episode 3
S6E3 / 15 Jan 2021
Episode 4
S6E4 / 22 Jan 2021
Episode 5
S6E5 / 29 Jan 2021
Episode 6
S6E6 / 05 Feb 2021
Episode 7
S6E7 / 12 Feb 2021
Episode 8
S6E8 / 19 Feb 2021
Episode 9
S6E9 / 26 Feb 2021
Episode 10
S6E10 / 05 Mar 2021
Episode 11
S6E11 / 12 Mar 2021
Episode 12
S6E12 / 19 Mar 2021
Episode 13
S6E13 / 26 Mar 2021
Episode 14
S6E14 / 02 Apr 2021
Episode 15
S6E15 / 09 Apr 2021
Episode 16
S6E16 / 16 Apr 2021
Episode 17
S6E17 / 23 Apr 2021
Episode 18
S6E18 / 30 Apr 2021
Episode 19
S6E19 / 07 May 2021
Episode 20
S6E20 / 14 May 2021
Episode 21
S6E21 / 21 May 2021
Episode 22
S6E22 / 28 May 2021
Episode 23
S6E23 / 04 Jun 2021
Episode 24
S6E24 / 11 Jun 2021
Episode 25
S6E25 / 18 Jun 2021
Episode 26
S6E26 / 25 Jun 2021
Season 7
Episode 1
S7E1 / 01 Jun 2021
Episode 2
S7E2 / 08 Jun 2021
Episode 3
S7E3 / 15 Jun 2021
Episode 4
S7E4 / 22 Jun 2021
Episode 5
S7E5 / 29 Jun 2021
Episode 6
S7E6 / 06 Jul 2021
Episode 7
S7E7 / 13 Jul 2021
Episode 8
S7E8 / 20 Jul 2021
Episode 9
S7E9 / 27 Jul 2021
Episode 10
S7E10 / 03 Aug 2021
Episode 11
S7E11 / 10 Aug 2021
Episode 12
S7E12 / 17 Aug 2021
Episode 13
S7E13 / 24 Aug 2021
Episode 14
S7E14 / 31 Aug 2021
Episode 15
S7E15 / 07 Sep 2021
Episode 16
S7E16 / 14 Sep 2021
Episode 17
S7E17 / 21 Sep 2021
Episode 18
S7E18 / 28 Sep 2021
Episode 19
S7E19 / 05 Oct 2021
Episode 20
S7E20 / 12 Oct 2021
Episode 21
S7E21 / 19 Oct 2021
Episode 22
S7E22 / 26 Oct 2021
Episode 23
S7E23 / 02 Nov 2021
Episode 24
S7E24 / 09 Nov 2021
Episode 25
S7E25 / 16 Nov 2021
Episode 26
S7E26 / 23 Nov 2021
Season 8
Episode 1
S8E1 / 01 Jan 2023
Episode 2
S8E2 / 08 Jan 2023
Episode 3
S8E3 / 15 Jan 2023
Episode 4
S8E4 / 22 Jan 2023
Episode 5
S8E5 / 29 Jan 2023
Episode 6
S8E6 / 05 Feb 2023
Episode 7
S8E7 / 12 Feb 2023
Episode 8
S8E8 / 19 Feb 2023
Episode 9
S8E9 / 26 Feb 2023
Episode 10
S8E10 / 05 Mar 2023
Episode 11
S8E11 / 12 Mar 2023
Episode 12
S8E12 / 19 Mar 2023
Episode 13
S8E13 / 26 Mar 2023
Episode 14
S8E14 / 02 Apr 2023
Episode 15
S8E15 / 09 Apr 2023
Episode 16
S8E16 / 16 Apr 2023
Episode 17
S8E17 / 23 Apr 2023
Episode 18
S8E18 / 30 Apr 2023
Episode 19
S8E19 / 07 May 2023
Episode 20
S8E20 / 14 May 2023
Episode 21
S8E21 / 21 May 2023
Episode 22
S8E22 / 28 May 2023
Episode 23
S8E23 / 04 Jun 2023
Episode 24
S8E24 / 11 Jun 2023
Episode 25
S8E25 / 18 Jun 2023
Episode 26
S8E26 / 25 Jun 2023
Season 9
Episode 1
S9E1 / 01 Jan 2024
Episode 2
S9E2 / 08 Jan 2024
Episode 3
S9E3 / 15 Jan 2024
Episode 4
S9E4 / 22 Jan 2024
Episode 5
S9E5 / 29 Jan 2024
Episode 6
S9E6 / 05 Feb 2024
Episode 7
S9E7 / 12 Feb 2024
Episode 8
S9E8 / 19 Feb 2024
Episode 9
S9E9 / 26 Feb 2024
Episode 10
S9E10 / 04 Mar 2024
Episode 11
S9E11 / 11 Mar 2024
Episode 12
S9E12 / 18 Mar 2024
Episode 13
S9E13 / 25 Mar 2024
Episode 14
S9E14 / 01 Apr 2024
Episode 15
S9E15 / 08 Apr 2024
Episode 16
S9E16 / 15 Apr 2024
Episode 17
S9E17 / 22 Apr 2024
Episode 18
S9E18 / 29 Apr 2024
Episode 19
S9E19 / 06 May 2024
Episode 20
S9E20 / 13 May 2024
Episode 21
S9E21 / 20 May 2024
Episode 22
S9E22 / 27 May 2024
Episode 23
S9E23 / 03 Jun 2024
Episode 24
S9E24 / 10 Jun 2024
Episode 25
S9E25 / 17 Jun 2024
Episode 26
S9E26 / 24 Jun 2024
Season 10
Episode 1
S10E1 / 29 May 2025
Episode 2
S10E2 / 29 May 2025Episode 3
S10E3 / 05 Jun 2025Episode 4
S10E4 / 12 Jun 2025Episode 5
S10E5 / 19 Jun 2025Episode 6
S10E6 / 26 Jun 2025Episode 7
S10E7 / 03 Jul 2025Episode 8
S10E8 / 10 Jul 2025Episode 9
S10E9 / 17 Jul 2025Episode 10
S10E10 / 24 Jul 2025Episode 11
S10E11 / 31 Jul 2025Episode 12
S10E12 / 07 Aug 2025Episode 13
S10E13 / 14 Aug 2025Episode 14
S10E14 / 21 Aug 2025Episode 15
S10E15 / 28 Aug 2025Episode 16
S10E16 / 04 Sep 2025Episode 17
S10E17 / 11 Sep 2025Episode 18
S10E18 / 18 Sep 2025Episode 19
S10E19 / 25 Sep 2025Episode 20
S10E20 / 02 Oct 2025Episode 21
S10E21 / 09 Oct 2025Episode 22
S10E22 / 16 Oct 2025Episode 23
S10E23 / 23 Oct 2025Episode 24
S10E24 / 30 Oct 2025Episode 25
S10E25 / 06 Nov 2025Episode 26
S10E26 / 13 Nov 2025
Keith Wickham
Simon Greenall
Jo Wyatt
Teresa Gallagher
Dashi
