The Oceana Series from Celestron features waterproof models for marine use. All are rubber covered to protect against rough handling. This feature-packed model includes a compass, reticle, rangefinder and individual focus. All provide maximum optical performance with BAK-4 prisms and multi-coatings for sharp images with high contrast and resolution. Each model has a large, 50mm objective lens to offer maximum image brightness even in low light conditions, like dusk and dawn.