New deep VLA D array H i observations of the highly inclined nearby spiral galaxy NGC 2683 are presented . Archival C array data were processed and added to the new observations . To investigate the 3D structure of the atomic gas disk , we made different 3D models for which we produced model H i data cubes . The main ingredients of our best-fit model are ( i ) a thin disk inclined by 80 ^ { \circ } ; ( ii ) a crude approximation of a spiral and/or bar structure by an elliptical surface density distribution of the gas disk ; ( iii ) a slight warp in inclination between 10 kpc \leq R \leq 20 kpc ( decreasing by 10 ^ { \circ } ) ; ( iv ) an exponential flare that rises from 0.5 kpc at R = 9 kpc to 4 kpc at R = 15 kpc , stays constant until R = 22 kpc , and decreases its height for R > 22 kpc ; and ( v ) a low surface-density gas ring with a vertical offset of 1.3 kpc . The slope of NGC 2683 ’ s flare is comparable , but somewhat steeper than those of other spiral galaxies . NGC 2683 ’ s maximum height of the flare is also comparable to those of other galaxies . On the other hand , a saturation of the flare is only observed in NGC 2683 . Based on the comparison between the high resolution model and observations , we exclude the existence of an extended atomic gas halo around the optical and thin gas disk . Under the assumption of vertical hydrostatic equilibrium we derive the vertical velocity dispersion of the gas . The high turbulent velocity dispersion in the flare can be explained by energy injection by ( i ) supernovae , ( ii ) magneto-rotational instabilities , ( iii ) ISM stirring by dark matter substructure , or ( iv ) external gas accretion . The existence of the complex large-scale warping and asymmetries favors external gas accretion as one of the major energy sources that drives turbulence in the outer gas disk . We propose a scenario where this external accretion leads to turbulent adiabatic compression that enhances the turbulent velocity dispersion and might quench star formation in the outer gas disk of NGC 2683 .