A marathon runner who tried to run his way around the Bermuda Triangle in an inflatable bubble was rescued by the U.S. Coast Guard on Saturday about 70 miles off the coast of Florida after he became exhausted, authorities said.

Reza Baluchi, a runner who advertised his human-powered trip across the ocean to Bermuda, down to Puerto Rico and back to southern Florida on his website, gave up his voyage and activated a locating beacon Saturday morning, days after refusing earlier requests to abandon the voyage, the Coast Guard said.

Rescuers aboard a MH-60 Jayhawk hoisted Baluchi to safety and he was flown to an air station in Clearwater, Florida, for a medical evaluation.

The Coast Guard said it first received a report about the strange craft in the ocean on Wednesday, and that crew members from Coast Guard Cutter Weber tried to convince Baluchi to abandon the planned 3,500-mile trip after noticing that the bubble was only stocked with water and protein bars, but he refused.

In a Thursday phone call from the Coast Guard to Baluchi, an official said he had “great concern” for Baluchi’s safety and that currents were likely to push him far north of his intended course, but the marathon runner said he had prepared for the journey for two years and wanted to continue.

Baluchi has twice run across the U.S., and in 2007 he ran around the perimeter of the country, according to his website.

The Coast Guard responds to a report of a man in a bubble off the coast of Miami on Wednesday. The marathon runner was rescued Saturday after becoming exhausted, the Coast Guard said. U.S. Coast Guard

— Phil Helsel