Before he passed out, he was on his ship. The waves had been high and mighty, moving the ship up and down roughly. So roughly in fact, that he fell off the ship and into the water, then had blacked out after losing too much oxygen. When he woke up, he was floating on the water, just near the sand of an island. He had quickly slightly swam to the shore, coughing up water. Just a few minutes after walking alongside the shore, he had found Luffy's unconscious body laying on the sand.
He had dragged Luffy to the foresty area, setting him on the short, vibrant grass before pressing his hand down on his upper stomach/lower chest for a few moments before standing up and exploring the island, having found (non poisonous) berries, Persimmons, Umes, and white strawberries, but no signs of civilization or previous inhabitants. There were weird animals, like bears and boars with bigger bodies and more stronger (although much stronger than normal ones (but still not anywhere near his strength) and aggressive.
He made his way back to Luffy after meeting the aggressive animals, then sat down next to unconscious man. He began thinking of things to do- try to build a raft of some sort and try to find their crews- use Haki to try to wake up Luffy (at worst resuscitate him)- because something was better than sitting and doing nothing. He had his eyes closed, keeping a calm heartbeat and head, deep in thought.