The Caldera is not only a palace. Harbor Market sells fire flakes at Red Tongue Flakes (Nara Jin, 2 copper a cone, 8 a bag, dragon-hot a silver), late noodles at Hwan's Night Noodles (4 to 7 copper a bowl), tea and Pai Sho at The Scented Coal (Madam Yulai; Ko the Tiles plays at the window and sells talk to more than one employer), weapons at The Red Anvil (Old Pitou, who has stamped unusual spearheads), and honest toolwork at The Warm Hammer (Smith Togaru, who refused a quiet chop and is having his coal stolen). The Ash Lantern inn on Harbor Street puts evacuees on floor mats for 4 copper or in a room for a silver. Ferryman Batsu runs public hops from 2 copper. These people are how a party learns the truth without storming a throne.
CRESCENT ISLAND holds the Fire Temple, damaged decades ago when Roku forced the Avatar State. Kaja remains in the Sanctuary Antechamber. Azane's relief cutter ties at the docks with manacles under the rice. A statue and shrine to Roku will grow here; the doors already matter.
ROKU'S ISLAND is a smoking ruin: caldera, ruined village path, foundations of Roku and Ta Min's house, evacuation beach, Spirit-echo ridge. No one living should stay. Scouts already pick the edges. Thin nights bring Roku and Fang.
EMBER ISLAND still entertains nobles. Hostess Lina at The Golden Pearl rents a back room she thinks is affair-mail; it is a Mandate dead-drop.
HIRA'A is a quiet town with a riverside stall, Green Shade, run by Herbalist Osha, who has already agreed to hide a noble woman with a famous last name if asked. Rina may arrive here. In later canon this town becomes her home.
LAMBAK ISLAND is a special region: Clan Longhouse (Chief Dumalaga), spirit-metal foundry (Dalisay, elderly, morally myopic, stockpiling for a dated operation), garrison (Kozaru). Autonomy is the official word. The Mandate is the actual customer.
YU DAO, in the western Earth Kingdom, is a Fire colony that has existed since 37 BG and already has mixed streets, a governor's terrace (Ryozen), a bakery basement resistance (Bohai), a public ferry (Wudao), and a smelter quay (Sarn, whose sister was 'reassigned' to a locked warehouse). Roku forbade further expansion. Roku is dead. This is the powder keg of the first year.
YUYAN FOREST, the Forest of Whispering Needles, holds Uzuku Yuyan's Master's Range. The school is rising. She will not take a contract on children.
ASHFERN HERMITAGE in the western hills hides Zeisan and Rioshon. The Guiding Wind's Unbound Circle camp sits in the mountains above the Fire & Air Center; Jinsa on the protest ridge has seen Mandate scribes copying temple guest lists.
SHU JING has Sword-sage Ozu's hillside forge, a White Lotus shopfront that will hide a child in the rafters if Amara asks.
Travel in the Fire Islands is by ferry, official barge, and, for the powerful, dragon. Official barges already turn back civilian boats that 'ask too many questions' about the eruption. That, too, is a hook.