Mungo's father used to work in a travelling circus as a wrestler and strong man. He wrestled Trolls and would have Elephants stand on him. Whilst the circus was in Fang, he entered the Deathtrap Dungeon, and was never to be seen again. This fuelled Mungo's passion for adventuring.
The Blue Marlin is revealed to be the name of his boat in The Port of Peril.