What survival strategy is necessary for life after the ozone layer is compromised by supernova radiation?

Sustaining life indefinitely deep underwater or underground away from the damaged surface ecosystem.

If a supernova event destroys a significant fraction of the ozone layer, the danger is not an instantaneous burst like heat, but a prolonged environmental catastrophe caused by intense solar UV radiation lasting months or years. While physical shielding like being indoors or underground protects against the initial heat and radiation pulse, once the environment changes permanently, survival requires complete separation from the UV-drenched surface. Deep underwater environments, or extensive subterranean habitats like mines, offer the only long-term refuge, provided the inhabitants can establish independent, sustained ecosystems without relying on the damaged surface biosphere for resources.