It will premiere in July 11.
The official website for the anime of “Free! Dive to the Future” has uploaded a new promo which you can see bellow:
Anime News Network describes the story as follows:
“In the new series, Haruka, who is attending college in Tokyo, meets Asahi again and reawakens his memories from his middle school years, including those of Ikuya. Makoto is working toward a new dream while he is in Tokyo together with Haruka. Rin has an unexpected meeting in Sydney. As they await their new futures, will they see a new fight ahead? Or will they instead confront the past they left behind?”
Via: Anime News Network