To start Home Delivered, you must talk to a man outside a bar on the small island near bridge control. He'll tell you about the villagers who have been disappearing, about how a mystic pool ties in with it all. He wants you to investigate.
Go to the swimming hole.
Locate the missing villagers.
Exit the cave.
After talking to the man, you can follow the river down to the entrance to the pool. the entrance is right near the water. Go in, and dive into the pool.
At the end of the pool the bottom gives away and there is a small underwater cave. Swim through, and appear on the other side, in a bigger cavern. In the water you can see the dead villagers, and at the far end you can see a shrine of some sort. Throughout the cave there are containers which you can loot as well as the Heron 2 relic. Exit the way you came.
As you are swimming back through the cave, you will be attacked by a croc. Mash the button and kill it, then head back to tell Steven about it. You'll tell him that it's been a croc thats killed the villagers, and he'll thank you for killing it.