Abstract: The Mare Island Naval Cemetery is located just outside of Vallejo, California. This historic naval cemetery was inspected in November 2022, and signs of slope instability were identified. Two follow-up inspections were conducted by geotechnical engineers and geologists from the US Army Engineer Research and Development Center. A preliminary site investigation showed that desiccation cracking was present and that seepage at the toe of the cemetery slope could contribute to long-term stability issues. Historic vegetation had also recently been cleared, exposing the soils and headstones. If left unaddressed, these factors could lead to slope instability at the site. Increased monitoring, regular surveys, seepage remediation, and reestablishment of vegetation are recommended to prevent future instabilities.