Senior Mechanical Engineer

ABOUT ENDURANCE Endurance is building the world's first modular subsea geothermal power plants, converting vast thermal resources under the ocean into gigawatts of baseload power. Backed by Founders Fund, Felicis, First Round Capital, and Point72 Ventures, our founding team includes veterans from SpaceX, Helion, Blue Origin, and Apple. We have completed multiple deep-ocean deployments to subsea volcanoes and are launching a long-term demonstration project this fall. By leveraging modular design, manufacturing scale, efficient drilling, and latent cooling on the seafloor, we are pioneering a new category of energy that outperforms traditional sources on environmental impact, deployment speed, and cost. WHAT YOU'LL BE DOING As a Senior Mechanical Engineer, you will own critical mechanical systems within our seafloor power plants. These systems must survive high pressure, corrosion, thermal cycling, mechanical loads, and long deployment durations in saltwater environments. You will design and deliver pressure-tolerant structures, thermal systems, fluid interfaces, deployment hardware, and mechanical subsystems that operate reliably on the ocean floor. This role blends rigorous analysis with hands-on hardware development. You will take ambiguous, high-risk mechanical systems including pressure vessels, structural frames, thermal interfaces, fluid systems, and deployment hardware and drive them from first principles to offshore deployment. This role requires deep mechanical intuition and extreme ownership. You will architect systems, design parts, release drawings, build prototypes, run tests, break hardware, and iterate until the system works reliably. If a machine fails on the seafloor, you will feel responsible for fixing it permanently. We are looking for someone who has personally built hardware, debugged mechanical failures in the lab or field, and understands the difference between a clean CAD model and a system operating in a harsh environment. KEY RESPONSIBILITIES - Architect and design critical mechanical systems from concept through offshore deployment - Perform first-principles analysis of loads, thermal behavior, sealing strategies, and failure modes - Design pressure-tolerant hardware, structural systems, and thermal interfaces for subsea environments - Develop robust sealing and corrosion mitigation strategies for long-duration saltwater exposure - Design assemblies including pressure housings, structural frames, fluid systems, and deployment mechanisms - Create detailed 3D CAD models, drawings, and tolerance stacks for complex hardware - Build and test prototypes to validate mechanical performance and uncover failure modes - Design and execute qualification tests including pressure testing, fatigue testing, thermal cycling, and corrosion exposure - Investigate hardware failures and implement permanent design improvements - Work directly with fabricators and suppliers to build hardware quickly and correctly - Collaborate with electrical, drilling, and subsea systems teams to ensure clean system integration - Participate in sea trials and field deployments to validate hardware performance QUALIFICATIONS - 6+ years designing and delivering complex mechanical systems in demanding environments - Demonstrated ownership of hardware from early concept through testing and deployment - Strong first-principles understanding of mechanics, materials, thermal systems, and failure modes - Deep proficiency in 3D CAD and mechanical design of complex assemblies - Experience designing hardware for harsh environments (subsea, aerospace, automotive, energy, robotics, etc.) - Proven ability to debug mechanical failures through testing and root-cause analysis - Strong intuition for structural load paths, sealing strategies, corrosion mitigation, and thermal management - Comfort working hands-on with hardware in a lab or shop environment - Ability to move quickly, close loops, and make good engineering decisions under uncertainty - High ownership mentality and accountability for system performance and reliability COMPENSATION, BENEFITS, & PERKS As a pre-revenue startup, Endurance Energy offers competitive base salaries and generous equity packages for full-time employees. Final base salary will be determined by an array of factors including internal equity, job-related knowledge, skills, and work experience. A key aspect of our compensation philosophy is that value creation should be aligned with rewards. Right now this means equity is a significant portion of every full-time employee's compensation. As the company matures, there will be continued evolution and changes to the total rewards and total compensation package. What will always be true is that if we win, we win together. Equity is granted to every full-time employee as a meaningful piece of ownership. We believe the people building the company should share directly in the value they create. In addition to a competitive base salary and equity, employees will receive all of our other great benefits and perks, including: - Benefits: Health, Dental, and Vision insurance coverage - Time Away: Flexible PTO including 12 paid company holidays - Global Fieldwork: Travel to fascinating deployment sites along oceanic ridges in locations like the Pacific Northwest, Hawaii, Iceland, Japan, New Zealand, and the Azores - Hands-on Experience: Participate in sea trials and deployment operations in partnership with leading oceanographic institutions - Cutting-edge Development: Work with technology that spans high-power electronics, marine systems, and clean energy - Impactful Work: Help solve one of the world's most pressing challenges - Dive Certification: Company-sponsored recreational dive certification - Other Perks: Access to the company boat, free meals and snacks, and the list goes on! If you’re selected for consideration, a recruiter will be able to discuss in greater detail.