You are especially skilled at navigating the winding tunnels under the earth. You gain darkvision out to a range of 60 feet. If you already have darkvision its range increases by 30 feet.
As an action you can close your eyes to gain tremorsense out to a 60-foot radius. In that radius, you can sense anything touching the ground. This special sense lasts for 1 minute, or until you open your eyes. Once you use this action you must finish a short or long rest before you can use it again.