Senior Mechanical Engineer (Electromechanical)

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. The Role Every watt the plant produces passes through electromechanical hardware. The power electronics live on the seafloor, so they are packaged in pressure-compensated, fluid-filled housings, cooled by seawater, and connected to the rest of the plant through high-power busswork and wet-mate and dry-mate connectors we design in-house. Every valve the plant actuates and every mechanism that moves is driven by subsea actuators and motors. We design, build, test, and deploy all of it. In this role you will focus on the hardware where electricity, fluid, and pressure meet: electronics cooling and thermal management; subsea packaging of high-power electronics, including dielectric fluids, compensation, penetrators, and feedthroughs; high-power busswork and electrical interfaces; wet-mate and dry-mate connectors; and actuators, motors, pumps, and mechanisms with their dynamic seals and magnetic couplings. You will share that scope with a few other engineers, and specific hardware will be yours end to end. You will work most closely with our power electronics engineers. Your First Year Help deliver the electromechanical hardware for our first commercial system, the first subsea geothermal plant to put power on a grid: the cooled, pressure-compensated electronics packaging, the busswork and connectors that carry its power, and the actuators that run it, all designed, built, qualified, and operating on the seafloor. How We Work Our mechanical engineering team is a small group of senior and principal engineers who split the plant's hardware between them. Each engineer owns their hardware end to end: requirements, design, drawings, build, test, and deployment. Principal engineers own the plant architecture, and you will be part of those decisions. We are looking for people who have built hardware, debugged it in the lab or the field, and want to own the result. Responsibilities • Own specific electromechanical hardware end to end: electronics cooling and enclosures, busswork and connectors, or actuators and mechanisms • Design high-power electrical interfaces: busswork, wet-mate and dry-mate connectors, contact and insulator design, dielectric sealing, and mate and demate mechanics • Design subsea packaging for high-power electronics: fluid-filled and pressure-compensated enclosures, dielectric fluid selection, penetrators, and feedthroughs • Design electronics cooling and thermal management: heat rejection from converter stacks through the enclosure to seawater, cold plates, and immersion cooling • Design subsea actuators, motors, pumps, and mechanisms: dynamic and rotating seals, magnetic couplings, position feedback, and fail-safe behavior • Translate electrical requirements (voltage, current, creepage, thermal) into mechanical designs, working day to day with the power electronics engineers • Design and build test setups for high voltage under hydrostatic pressure, insulation resistance, partial discharge, thermal performance, and long-duration immersion • Lead root-cause investigations on connector, enclosure, and actuator failures and implement corrective actions • Define interfaces with the valves and primary structures owned by your peers • Work directly with machine shops, molders, and specialty suppliers on contacts, insulators, seals, and precision mechanisms • Contribute to plant-level electrical architecture and packaging decisions alongside our principal engineers • Create detailed 3D CAD models, drawings, and tolerance stacks for electromechanical assemblies Basic Qualifications • Bachelor's degree in mechanical engineering, electrical engineering, or a related engineering discipline • 6+ years of professional experience designing electromechanical hardware (connectors, actuators, mechanisms, or electronics packaging) for demanding environments • Ownership of at least one electromechanical component from concept through qualification and fielded use Preferred Skills and Experience • Experience designing subsea electrical connectors, penetrators, busswork, or actuators, or equivalent experience with spacecraft mechanisms, downhole tools, or power electronics packaging for aerospace or automotive • Hands-on experience with dielectric fluids, pressure compensation, and sealing high voltage against seawater • Experience with dynamic and rotating seals, magnetic couplings, and the failure modes of mechanisms in long-duration service • Experience with thermal management of power electronics, including liquid- or immersion- cooled systems • Working knowledge of high-voltage design and test: creepage and clearance, insulation resistance, partial discharge • Experience sizing motors and actuators and integrating electronics into mechanical assemblies • Experience at a small or fast-moving hardware organization, where you had to make good engineering decisions with incomplete information and limited resources • A track record of taking on increasing responsibility and delivering something difficult early in your career • Experience on an engineering competition team (Formula SAE, Baja SAE, RoboSub, rocketry, or similar) or an equivalent self-directed hardware project 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.