Season 8 and the series conclude with Dexter facing impossible odds. With a hurricane threatening Miami, Dexter becomes determined to end things.
I Love You Deb — Daniel Licht
Dexter chooses to mercifully shut off Debra's life-support. He carries his sister's sheathed body out to "The Slice of Life", upon which he drives the boat out to sea.
Dexter drops Debra's body into the water and drives his boat directly into the hurricane.
Later, in Argentina, Hannah reads a report about Dexter's presumed fate.