The GPSMAP 76 is designed to provide precise GPS positioning using correction data obtained from the Wide Area Augmentation System. This unit features a built-in quad helix antenna for superior reception and can provide position accuracy to less than three meters when receiving WAAS corrections. The GPSMAP 76 has an internal memory capacity of eight megabytes. In addition, it comes with a built-in basemap of cities, coastlines, lakes, rivers, interstates, and interstate exit information and a database of nautical navaids. This unit has eight megabytes of internal user memory for storing optional MapSource detailed maps, including marine cartography. This memory is preloaded from the factory with worldwide cities (populations greater than 200,000) and nautical navigation aids such as lights, buoys, sound signals and day beacons. The GPSMAP 76 is also preloaded with tide data for the United States. An extra-large display measuring 1.6"W x 2.2"H gives users a clear view of information, while a waterproof case means the GPSMAP 76 will keep working well even if it's been submerged in water. Even more amazing, this unit will actually float if accidentally dropped in the water.