SCP-3531 is a Boeing 737 airliner. SCP-3531 is unremarkable in both exterior and interior appearance, and is non-anomalous when not in flight. However, photographs, videos, and audio recordings taken within SCP-3531 during flight show various forms of aquatic-based anomalous phenomena, as well as the manifestation of several humanoid figures acting as flight attendants on board. Despite this, observers remain either ignorant or unwilling to acknowledge the phenomena.