Circuit de Monaco downhill again to a double right-hander called "Portier," named after region of Monaco, before heading into the famous tunnel, a unique feature of a Formula One circuit. (Until 2009 only one other circuit, Detroit in 1982–88, featured a tunnel, but the F1 series now includes racing at the Yas Marina Circuit in Abu Dhabi, which presents a shorter tunnel at the exit of the pit lane.) As well as the change of light making visibility poor, a car can lose 20–30% of its downforce due to the unique aerodynamic properties of the tunnel. The tunnel also presents a unique problem
Yas Marina Circuit theme park, a water park, as well as residential areas, hotels and beaches. The circuit has five grandstand areas (Main Grandstand, West Grandstand, North Grandstand, South Grandstand and Marina Grandstand (aka Support)) and part of its pit lane exit runs underneath the track. It also houses a team building behind the pit building, Media Center, Dragster Track, VIP Tower and Ferrari World Theme Park. Additionally, one of the run-off areas runs underneath the West grandstand. The circuit was built by main contractor Cebarco-WCT WLL, under contract from developer Aldar Properties. Among the sub-contractors involved were KOH AH HING from Malaysia