Decision Time is twenty-sixth and final episode in Season 1 of Mako: Island of Secrets. It premiered on Netflix on September 15, 2013.
With the full moon fast approaching, Zac prepares to give up his powers while the mermaids prepare to return to their pod. Evie is upset with Zac for keeping his secret from her for so long but agrees to keep his secret until after the full moon. However, Cam manipulates Evie to keep Zac from going to Mako Island that night and possibly interfering with his true plan. The girls eventually realize that Cam is planning to become a merman himself so he can rule Mako Island with the trident. In the process, Nixie finally realizes her mistake in trusting Cam. The girls take Rita's Moon Rings and head to Mako to stop Cam. Meanwhile, Zac also realises what Cam is up to and heads to Mako as well. The four come together with their powers and destroy the trident, preventing Cam from executing his plan. In the aftermath, Rita grants the mermaids their own Moon Rings for saving the Moon Pool. Zac remains a merman, which means the pod can't return to Mako yet. After Evie reconciles with the girls, Zac, Sirena, Lyla, and Nixie swim into the ocean together.
- Lyla - Lucy Fry
- Nixie - Ivy Latimer
- Sirena - Amy Ruffle
- Zac Blakely - Chai Hansen
- Cam Mitchell - Dominic Deutscher
- Evie McLaren - Gemma Forsyth
- David - Rowan Hills
- Carly Morgan - Brooke Nichole Lee
- Rita Santos - Kerith Atkinson
- This is the last episode to feature Ivy Latimer and Lucy Fry as Nixie and Lyla.
- This is the final appearance of the Trident Cave.