That funny-looking building with the gigantic solar panels is the Natural Energy Laboratory of Hawaii Authority (NELHA). This 'zero-net energy facility' was voted one of the USA's 10 greenest buildings in 2007. Learn about OTEC and research into alternative and renewable-energy technologies at NELHA's public presentations (on Monday). Come on Wednesday and Friday for tours of sustainable aquaculture facilities like Kampachi Farms and Big Island Abalone, or Tuesday and Thursday for tours of Ke Kai Ola and Kanaloa Octopus Farm. Reservations required.

About 40 businesses call NELHA's HOST Park home, including Kampachi Farms, the aquaculture gurus responsible for yellowfin tuna seen on haute island restaurant menus.

The turnoff is just over a mile south of Kona International Airport, between Miles 94 and 95.