PORT VILA, Vanuatu (AP) — A decade ago, when John Warmington first explored the reef near his home in Havannah Harbor, Vanuatu, it was teeming with life. Corals stretched upward like an underwater forest, with branching staghorns in golden hues, sprawling plate corals, and schools of vibrant fish weaving through the maze. “We knew every corner of that reef. It was like family to us,” Warmington recalled. John Warmington, who has dived more than a thousand times in the same section of reef off