H2o episode's:

season 1;

#1. "Metemorphisiss"
#2. "Pool Party"
#3. "Catch Of the Day"
#4. "Party Girls"
#5. "Somethings Fishy"
#6. "Young Love"
#7. "Moon Spell"
#8. "Denman Affair"
#9. "Dangerous Water's"
#10. "The Camera's Never Lie"
#11. "Sink or Swim"
#12. "The Siren Effect"
#13. "Shipwrecked"
#14. Surprise!
#15. "The Big Chill"
#16. "Lovesick"
#17. "Under The Weather"
#18. "Bad Moon Rising"
#19. "Hurricane Angela"
#20. "Hook, Line, and Sinker
#21. "Red Herring"
#22. "Fish Out of The Water"
#23. "In Too Deep"
#24. "Love Potion #9"
#25. "Dr. Danger"
#26. "A Twist In The Tail"

season 2;

#1. "Control"
#2. "Fire and Ice"
#3. "Double Trouble"
#4. "Emma Rebel"
#5. "Hocus Pocus"
#6. "Pressure Cooker"
#7. "Wrong Side of The Track's"
#8. "In Hot Water"
#9. "Riding For A fall"
#10. "Unfamothable" or "Missed The Boat"
#11. "In Over Our Heads" or "Treasure Hunt"
#12. "Fish Fever" or "Monster"
#13. "Moonwalker" or "Camping on Mako Island"
#14. "Cleo vs. Charlotte" or "Get Off My Tail"
#15. "Irresistable"
#16. "Vision"
#17. "Moonstruck"
#18. "The Heat Is On"
#19. "The Gracie Code" (part 1)
#20. "The Gracie Code" (part 2)
#21. "Then There Were Four"
#22. "Bubble Bubble Toil and Trouble"
#23. "Reckless"
#24. "Three's Company"
#25. "Sea Change"
#26. "Finale"

season 3;

#1."Tail Be Gone"
#2. "Swim Away"
#3. "New Water's"
#4. "A Secret Untold"
#6. "Beyond The Wave's"
#8. "A Tail Brocken"
#?. "Wave's Above Water"
#?. "A Tail Told"


ps. Bella's new power is to freeze water.
and the episode list for season 3 might be missing some episode's like the following: 5,7. Sorry about that! The new guy's name is Will. He unleashes a new force over Mako and turn's against them. While Lewis get's lost in a hurricane, Cleo, Bell,Rikki, and Mrs. McCartney(Lewis' mom) look for him and it start's to rain! That's all i know for now!!