Till now - only dolphins could communicate underwater - now you can too! Based on text messaging technology, the UDI system allows divers to transmit pre-saved messages to other divers in the network, at a range of up to 500 meters (550 yards). SOS / Homing Procedure The UDI SOS and Homing features allow direct navigation to a diver who has sent an emergency SOS message or to a boat unit that has transmitted a homing signal. SOS: A diver in distress can send an SOS signal to other divers or to a boat unit. The receiving diver acknowledges the SOS call and receives graphical 3D instructions on his UDI unit that allow him to navigate his way to the diver in distress and provide assistance. A Boat unit: An optional system to communicate with the UDI, is the UDI boat unit. It is a compact, lightweight & easy to use. The boat unit supports 4 different networks (each of 14 divers) and is built with high power transmitter. The system comes in a water resistant suitcase, extra long battery power and external power connection. The boat unit enables text message communication with the underwater divers. It also allows divers to navigate their way back to the boat using its homing capabilities. Homing: When a diver sends a Remote Homing message to a boat unit, the boat unit transmits a homing signal that enables the diver to easily locate the boat. He then follows the graphical instructions on his screen and easily locates his target.