There are various possible endings in Wadanohara and the Great Blue Sea.
This is the second "Normal End". Listed is how this End is reached and what happens in this End.
To get to this ending, one must have played The Red Sea Witch ending (the first Normal End) first.
Wadanohara finds Sal and an injured Samekichi. When the player talks to Samekichi, a cutscene starts. Sal gives Wadanohara an option to trust Sal to save the sea and Samekichi. In the second playthrough of this cutscene, the player will have the option to not trust Sal. If that option is chosen, Sal will attack Samekichi once more. After a moment, Wadanohara gets up and, with the power of her Father's staff, restores the sea, sacrificing her own life in the process. The final scene shows Samekichi regretting how he couldn't do anything and that a world without Wadanohara is worthless to him. In the end, Samekichi dives into the water. It is unknown if Samekichi commits suicide but it is heavily implied, regarding his emotional state.