Here is a list of episodes from the Octonauts series, organized by season.
Season 1 (2010–2011)
1. The Whale Shark
2. The Giant Squid
3. The Crab and Urchin
4. The Walrus Chief
5. The Flying Fish
6. The Enemy Anemones
7. The Orcas
8. The Great Algae Escape
9. The Remipedes
10. The Speedy Sailfish
11. The Blobfish Brothers
12. The Sea Snakes
13. The Monster Map
14. The Lost Sea Star
15. The Albino Humpback Whale
16. The Giant Kelp Forest
17. The Oarfish
18. The Narwhal
19. The Midnight Zone
20. The Snapping Shrimp
21. The Snot Sea Cucumber
22. The Giant Jelly
23. The Hermit Crabs
24. The Decorator Crab
25. The Pirate Parrotfish
26. The Mimic Octopus
27. The Mixed-Up Whales
28. The Dwarf Lantern Shark
29. The Vampire Squid
30. The Scary Spookfish
31. The Slime Eels
32. The Cookiecutter Sharks
33. The Enormous Elephant Seal
34. The Beluga Whales
35. The Hungry Pilot Fish
36. The Giant Spider Crab
37. The Jellyfish Bloom
38. The Baby Dolphin
39. The Jawfish
40. The Sardine School
41. The Eel Ordeal
42. The Electric Torpedo Rays
43. The Crafty Cuttlefish
44. The Kelp Monster Mystery
45. The Humuhumunukunukuapua’a
46. The Colossal Squid
47. The Dolphin Reef Rescue
48. The Narwhal Rescue
49. The Sunfish
50. The Midnight Zone (Double Episode)
Season 2 (2012–2013)
1. The Lionfish
2. The Giant Jelly
3. The Manta Rays
4. The Snot Sea Cucumber
5. The Swashbuckling Swordfish
6. The Manatees
7. The Fiddler Crabs
8. The Sea Pigs
9. The Gulper Eels
10. The Loggerhead Sea Turtles
11. The Leafy Sea Dragons
12. The Poison Dart Frogs
13. The Amazon Adventure
14. The Saltwater Crocodile
15. The Giant Squid (Double Episode)
16. The Flying Fish
17. The Pelicans
18. The Mimic Octopus
19. The Sawfish
20. The Blobfish Brothers
21. The Swamp Gators
22. The Sea Skaters
23. The Great Swamp Search
24. The Giant Clam
25. The Kelp Monster Mystery
26. The Humpback Whales
27. The Dolphin Reef Rescue
28. The Deep Sea Adventure (Double Episode)
Season 3 (2014–2015)
1. The Sea Pig
2. The Immortal Jellyfish
3. The Cone Snail
4. The Water Bears
5. The Sea Sponge
6. The Siphonophore
7. The Fiddler Crab
8. The Seahorses
9. The Red Rock Crabs
10. The Urchin Invasion
11. The Lion's Mane Jellyfish
12. The Sea Pigs
13. The Oarfish
14. The Cone Snail
15. The Immortal Jellyfish
16. The Tiger Shark
17. The Seahorses
18. The Yeti Crab
19. The Manta Rays
20. The Dolphin Reef Rescue
21. The Cone Snail
22. The Flying Squirrel
23. The Saltwater Crocodile
24. The Loggerhead Sea Turtle
25. The Kelp Monster Mystery
26. The Giant Clam
Season 4 (2015–2016)
1. The Giant Squid
2. The Coconut Crabs
3. The Siphonophore
4. The Tiger Shark
5. The Lion's Mane Jellyfish
6. The Water Bears
7. The Narwhal Adventure
8. The Colossal Squid
9. The Orcas
10. The Jellyfish Bloom
11. The Sunfish
12. The Loggerhead Sea Turtle
13. The Giant Spider Crab
14. The Crafty Cuttlefish
15. The Sardine School
16. The Kelp Monster Mystery
17. The Slime Eels
18. The Baby Dolphin
19. The Hermit Crabs
20. The Blobfish Brothers
21. The Vampire Squid
22. The Great Christmas Rescue (Special)
23. The Great Penguin Race (Special)
24. The Octonauts and the Operation Deep Freeze (Double Episode)
Octonauts Specials
These are longer episodes or TV specials that sometimes aired separately from the regular seasons:
1. The Over, Under Adventure
2. The Amazon Adventure
3. The Operation Deep Freeze
4. The Octonauts and the Caves of Sac Actun
5. The Ring of Fire
