Our work proposes a haptic interaction technique for the rendering of isosurfaces. A virtual contact point is computed corresponding to the most suitable isovalue position in a 3D data grid. With this method we can freely explore and understand complex data fields without explicitly computing the geometry of the isosurface, nor having any intermediate representation. Thus, a very fast haptic rendering loop is easily obtainable. Moreover, our approach is flexible because the contact detection and force feedback computation are automatically adapted to take into account regions presenting high spatial frequency data as in the CFD case.