What do the 4 different coloured flags mean in Antarctica? You’ve probably seen them in my videos but not paid much attention to why they are the colour they are, and what they’re used for. Now that you’re consciously thinking about them, I’ll let you know. Both the green and the red flags are used to mark SAFE routes, usually on roads or pre established walking trails. Black flags mark danger ⚠️ like crevasses and cracks. Blue flags are used to indicate fuel lines or refueling infrastructure. T