With a gradually descending bottom slope beneath the inlet, the basin lacks strong internal thresholds (abruptly steepening slopes) that often isolates the deep of fjord basins from imported tidal currents, thus leaving the Botn basin 'hydrodynamically open' (with very weak topographical stratifications). Thus, the annually induced stagnation depth varies with the volume and energy of the tidal instream in the critical time when the spring flood dilutes the incoming water rapidly, and accumulating differences along the current shear creates the stratification. Naturally there is also a bottom water stratification between semi-ventilated deep water (uninhabitable but not rotten) and totally isolated poisonous bottom water.