Senior Mechanical Engineer

Senior Mechanical Engineer | Seattle, WA

Endurance is developing modular seafloor geothermal power plants that harness the vast thermal energy beneath the ocean floor to provide gigawatts of clean, reliable energy. We're addressing the critical power bottleneck facing AI infrastructure development while creating a path toward energy independence and decarbonization across the globe.

Backed by premier venture capital firms including First Round Capital and Point72 Ventures, our exceptional founding team includes veterans from SpaceX, Robinhood, Helion, and Neuralink, with specialized expertise in complex thermal and fluid systems and business development.

We are looking for a Senior Mechanical Engineer to design and deliver the core hardware of our seafloor power systems. 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.

The Role

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. 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

Benefits & Perks

Hands-on Experience: Work directly with large-scale, cutting-edge clean energy systems and participate in sea trials

Impact-Driven Work: Contribute to solving one of the world’s most pressing challenges—clean, reliable power generation

Competitive Compensation: Competitive salary and equity compensation

Benefits: Health, dental, and vision coverage

PTO: Unlimited with advanced notice

Endurance is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.