For nearly two decades, my friend Terry, a Vietnam-era Navy veteran, shared an extraordinary bond with a giant Pacific manta ray named Willy. Every day, Willy would slap his massive wing against the hull of Terry’s boat, calling him to the sea. Terry would slip on his SCUBA gear, plunge into the water, and ride on Willy’s back through the crystalline waters of Isla San Benedicto, a remote volcanic island 250 miles offshore. But life moves on, and Terry hadn’t seen Willy in over ten years.