Yoga boat pose, or navaa-saana, is a core strengthening exercise that tones the abs and back muscles. To do this pose, start by sitting with your knees bent and feet flat on the ground. Lift your feet off the ground and extend your legs, keeping your toes pointed out. Place your hands behind your knees and raise your chest and shoulders as you lean back. Hold the pose for 30 seconds to one minute, then release. This pose strengthens the abdomen and back muscles, increases balance, and helps build strength and endurance.