GeometryCollection Interface

Bounding box of the coordinate range of the object's Geometries, Features, or Feature Collections. The value of the bbox member is an array of length 2*n where n is the number of dimensions represented in the contained geometries, with all axes of the most southwesterly point followed by all axes of the more northeasterly point. The axes order of a bbox follows the axes order of geometries. https://tools.ietf.org/html/rfc7946#section-5