Refer to the following pseudocode sequence which is used to process geographical coordinates in a flight navigation system:

waypoints = [
    [51.5074, -0.1278],
    [48.8566, 2.3522],
    [40.7128, -74.0060],
    [35.6762, 139.6503]
]

for i = 0 to 3
    distance = calculate_distance(waypoints[i][0], waypoints[i][1])
    print("Distance to waypoint ", i, " is ", distance)
next i

State the specific type of data structure represented by the variable waypoints.