The broader impact/commercial potential of this Small Business Technology Transfer (STTR) Phase I project is the enabling capabilities in applications that call for both in-air and underwater operations. The aerial-underwater drones are the first drones that can fly in air, swim in water, and transition swiftly between air and water. This project aims to equip the drones with video transmission capabilities through underwater acoustic communication so that the drone need not be tethered to operate underwater. With the enabling capabilities, the drone is useful in critical infrastructure mapping, coastal environment monitoring, emergency response, coastal surveillance, and search and rescue operations. The underwater video transmission technology can also be applied to other platforms to extend underwater wireless and mobile internet. The capability, in turn, has the potential to enable Internet of Underwater Things. The commercial potential of the project addresses the pain points of the existing products: the low data rate and large form factor. The enhanced drone will enable the hybrid vehicle to create a new market that is unserved by either Autonomous Underwater Vehicles (AUVs) or Unmanned Aerial Systems (UASs).This Small Business Technology Transfer (STTR) Phase I project will design and prototype a small form factor acoustic communication system for aerial-underwater drones enabling them to achieve high data-rate video transmission over underwater wireless links. The intellectual merits of the proposed acoustic communication system include: 1) real-time hardware implementation of a novel MIMO (multiple-input-multiple-output) transmitter on an embedded GPU (Graphic Processing Unit) such that the system can be powered by battery and be fit in a small water-proof container, 2) real-time hardware implementation of a Turbo equalization receiver on an FPGA (Field Programmable Gate Array) platform to combat the huge Doppler spread and long multipath echoes of acoustic channels, 3) video transmission by a high information data rate of more than 300 kbps over underwater acoustic links, and 4) integration of the small form factor acoustic transmitter with the aerial-underwater drones without interfering with the operation of the drones.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.