The build follows the usual route of some electronics wedged into a pelican-style waterproof case — which is a ... of this are controlled via an Arduino Mega 2560, with copious amounts of ...

It’s a significant update. The Arduino UNO and Arduino Mega 2560 update the Duemilanove and Mega respectively. They now use an ATMega8U2 instead of an FTDI USB to serial converter chip.