Reza Ghorbani, PhD Associate Professor Department of Mechanical Engineering University of Hawai'i, Mānoa Short relatively deep tidal basins, which are connected to the open sea by a narrow strait, may exhibit either an amplified (resonant), or damped (choked) response to the tide at the entrance. The sole mode added to this system when the basin communicates with a tidal sea through a narrow strait is the pumping or Helmholtz mode, characterized by a periodic mass exchange through the narrows and associated spatially uniform elevation change within the basin. This is generally also the most energetic mode of such a basin.