Four boys freed, eight to go - the ongoing Thai cave rescue operation in pictures

Ever since the remarkable first images emerged of Thai schoolboys huddled alive and relatively well, three kilometres into a cave system, a race has been on to extract them before too much water, or too little oxygen, runs its course.

Here is a snapshot of the huge logistic initiative to bring out the 12 schoolboys and their coach, with divers this morning successfully navigating the flooded caves in Mae Sai district with four of the boys.

Eight of the boys and their coach are still trapped, and it is increasingly becoming a race against time, with the second rescue operation for a further three boys set to begin sometime later today (NZT).

Here is the story so far in images: