Every Reykjavik neighbourhood has a geothermal pool, and they are where the city actually socialises: hot pots at varying temperatures, a steam room, and conversation. The large lagoons are genuinely spectacular and worth doing once, but the local pools cost a fraction and tell you more about Iceland. Shower rules are strict and non-negotiable — read the signs.
Our notes
Pair a lagoon visit with the arrival or departure day, when it sits neatly between the airport and the city, and use neighbourhood pools for the days in between.