Before you enter any public pool or geothermal lagoon in Iceland (including the Blue Lagoon), you are required by local law and culture to shower naked and wash thoroughly with soap. In most countries, people shower with their swimsuits on; in Iceland, this is considered unhygienic and disrespectful.

The pools use minimal chlorine because they rely on the "clean entry" of their guests. Most municipal pools have communal showers, though newer high-end spas like Sky Lagoon offer private stalls. Don't try to skip this—pool wardens are often on-site and will politely but firmly send you back to the showers if they see you heading to the water dry.