finally tonight here, we said we would stay on it, and tonight, inside that miracle cave rescue. what we never knew from the divers themselves. abc's matt gutman tonight. >> reporter: their daring mission captivated the world. tonight, we're learning that the international rescue squad had peered that nearly half of that thai soccer team would not survive the grueling journey out of that cave. >> how many of you? >> reporter: what did you think the chances were for success? >> we always knew we could get them out. it was whether we could get them alive or not. >> reporter: one of the big concerns for divers like jason mallinson, the boys panicking. >> potential for them to kill themselves, there was to sensual for them to kill us. >> reporter: so, rescuers administered a powerful sedative, ketamine, to knock the boys out cold. they used specialized equipment,