Background: Intensive care unit nurses are providing care to COVID-19 patients in a stressful environment. Understanding intensive care unit nurses’ sources of distress is important when planning interventions to support them. Purpose: To describe Canadian intensive care unit nurse experiences providing care to COVID-19 patients during the second wave of the pandemic. Design: Qualitative descriptive component within a larger mixed-methods study. Participants and research context: Participants were invited to write down their experiences of a critical incident, which distressed them when providing nursing care. Thematic analysis was used to analyze the data. Ethical considerations: The study was approved by the ethics committee at the researchers’ university in eastern Canada. Results: A total of 111 critical incidents were written by 108 nurses. Four themes were found: (1) managing the pandemic, (2) witness to families’ grief, (3) our safety, and (4) futility of care. Many nurses’ stories also focused on the organizational preparedness of their institutions and concerns over their own safety. Discussion: Nurses experienced moral distress in relation to family and patient issues. Situations related to insufficient institutional support, patient, and family traumas, as well as safety issues have left nurses deeply distressed. Conclusion: Identifying situations that distress intensive care unit nurses can lead to targeted interventions mitigating their negative consequences by providing a safe work environment and improving nurses’ well-being.