Situational irony when there is a circumstance where the outcome is doesn't match with what was expected, but it is also more generally understood as a situation that includes contradictions or sharp contrasts. Stevenson uses situational irony in many ways to add humor to the novel.
For instance, after Jim successfully boards the Hispaniola he exclaims that he has "come aboard to take possession of this ship, Mr. Hands; and you’ll please regard me as your captain until further notice’... [he] ran to the colour lines, handed down [the pirates] cursed black flag, and chucked it overboard. ‘God save the king!’ said I, waving my cap. ‘And there’s an end to Captain Silver!’...‘I reckon,’ [Israel Hands] said at last,...'Cap’n Hawkins" (231-232). This is an excellent example of verbal and situational irony because Jim - a small nine year old boy and first time sailor - was able to recapture a large ship and win a fight against a intimidating, manipulative, and experienced pirate. There is a David and Goliath aspect to this event, the audience doesn't believe there is anyway Jim could possibly man a ship on his own, let alone single highhandedly kill a pirate.
After his heroing recapture of the Hispaniola Jim returns "home to the stockade and boast of [his] achievements. Possibly [he] might be blamed a bit for [his] truantry, but the recapture of the HISPANIOLA was a clenching answer, and [he] hoped that even Captain Smollett would confess [he] had not lost [his] time (252). The irony lies in the youthful mind of Jim, even though he fought and killed Israel Hands and single handedly returned the ship to the rightful side, he still worries that he will be scolded by Captain Smollett like a misbehaving child.
Another example of situational irony takes place when Doctor Livesey tells Jim that "[Billy Bones] should lie for a week...that is the best thing for [Bones] and [Jim] ; but another stroke would settle him.’ He has to stay laying for an week but he has been found after an day of hiding (24). Here the irony is form from Livesey diagnosis for Billy Bones to stay in bed for a week, however he is on the run from Pew who found him only after a day. This