Embodiments of footwear to optimize propulsion while swimming in the water and walking on land, in particular, amphibious footwear capable of duty on land and in the water as well as versions that are optimized for predominantly use in the water for swimming. The exoskeleton amphibious footwear reduces metabolic demand of walking and swimming while also improving gait speed and swim speed. This is accomplished by assisting plantar flexion during land mode, and assisting dorsiflexion in water mode.