You can really see the chip in the lens (top, slightly to the left). It's refracting either the strobe or focus light. Either way, a good lesson to keep the lights further behind the dome.
Fri Feb 8 14:25:30 2019
14°C, depth 28 m
Wied iż-Żurrieq, Malta
f/3.2, 1/20, ISO 100, 31mm
Wet lens: AOI UWL-09 Wide Angle