Despite being named a swamp, the landscape seen in "Fright of Passage" appears more like a rocky cove with trees, bushes, grass, and a babbling brook. This stream harbors algae that glows when the Northern Lights - called "Aurvandil's Fire" - appear every ten years. It leads to the Berk, which is just at the south of the swamp.
Hiccup sets out to study the Flightmare dragon during the events of "Fright of Passage", which appears on Berk every 10 years. Astrid comes along, but has vengeance on her mind, to avenge a slight made to her relative, Fearless Finn Hofferson.