Practice sextant navigation without a sea horizonThe key to learning celestial navigation is practice, but how can you practice without a natural water horizon The time-honored solution is an artificial horizon made from a tray of fluid water, oil, even mercury. This simple device from Davis uses water to reflect sun through shades to permit accurate sights. Includes two sun shades, lid and directions. Folds into small carrying case, just add water 8.5" x 8.75" x 2.5"