Portsmouth Harbor Lighthouse is located on Coast Guard Station Portsmouth Harbor in New Castle, NH. No reservations are needed; tours are on a first come, first served basis. Children must be 42 inches tall to climb to the top, and adults are not permitted to carry children up the stairs. Visitors get to climb to the lantern room to enjoy the magnificent view and to see the fourth-order Fresnel lens up close. Volunteers will tell visitors about the history of the light station, and there will be souvenirs for sale. There are 44 stairs to the watch room and a 7-rung ladder to the lantern room. Flat shoes (not sandals or flip-flops) are strongly recommended to climb the ladder into the lantern room.