Admiral Fowle’s Piscataqua River Tidal Guide
(Not for Navigational Purposes)


Portsmouth, arguably the first town in this country not founded by religious extremists, is bounded on the north and east by the Piscataqua River, the second, third, or fourth fastest-flowing navigable river in the country, depending on whom you choose to believe.

The Piscataqua’s ferocious current is caused by the tide, which, in turn, is caused by the moon. The other player is a vast sunken valley — Great Bay — about ten miles upriver. Twice a day, the moon drags about seventeen billion gallons of seawater — enough to fill 2,125,000 tanker trucks — up the river and into Great Bay. This creates a roving hydraulic conflict, as incoming sea and the outgoing river collide. The skirmish line moves from the mouth of the river, up past New Castle, around the bend by the old Naval Prison, under Memorial Bridge, past the tugboats, and on into Great Bay. This can best be seen when the tide is rising.

Twice a day, too, the moon lets all that water go. All the seawater that just fought its way upstream goes back home to the ocean. This is when the Piscataqua earns its title for xth fastest current. Look for the red buoy, at the upstream end of Badger’s Island, bobbing around in the current. It weighs several tons, and it bobs and bounces in the current like a cork.

The river also has its placid moments, around high and low tides. When the river rests, its tugboats and bridges work their hardest. Ships coming in laden with coal, oil, and salt do so at high tide, for more clearance under their keels. They leave empty, riding high in the water, at low tide, to squeeze under Memorial Bridge.