The City of Portsmouth offers these discounts:
Indoor Pool (located on Andrew Jarvis Drive, next to Portsmouth High School): military pay the resident rate for use of the pool. Children under 48" tall must be accompanied by an adult.
Robert P. Sullivan Boat Launch (located on Peirce Island): Active duty military and veterans receive a 50% discount which equals:
Kayaks, canoes, paddleboards and other non-motorized craft - $5 per launch or $50 season pass. Motorized, jet skis, sail boats or other registered craft - $10 per launch or $87.50 season pass.

Visit the Blue Star Museums website for the NH museums that participate in the program and offer free admission to active duty military from 18 May - 2 September 2024. Many museums extend the free admission to their whole season.
In Greater Portsmouth they include:
Portsmouth Historical Society John Paul Jones House Museum
Moffatt-Ladd House
Strawbery Banke Museum (ice skating is half-price)
Children's Museum of NH
Seacoast Science Center