I have re-watched a clearer version of the preview from the SBS site itself and could see a bit more from the original clip which was captioned and had a wider screen.
Land could be seen at the top right corner of this shot so they were probably not so far out in the vast ocean.
Ji Won is holding a paddle and there is another net in the water on Sang Hyun’s left (white arrow). Looks like they were fishing and the raft should be secured to the 2 piles on both sides.
The above caption reads ‘an expected tyhoon strikes’.
There seems to be a shallow area at bottom right (white arrow) so they are probably near to shore.
Is there a possibility of reef sharks in shallow water?
What Sang Hyun was so focused on should be the fishing net visible at bottom right. Perhaps he was going to hit what he had caught with that wood. A piece of rope securing the raft can also be seen at bottom right.
The above caption reads ‘the will to survive is completely snatched away’ which could be referring to the fish struggling in the net.
The next shot below of the ferocious shark attacking the fish head with the caption ‘an unexpected shark’s counter attack’ should be from another footage as no one in their right mind would want to mess with a hungry shark within biting distance.