One of 'sister' in SBS5 , Jany send me the both postcard last year. She live in Puerto Rico.
Puerto Rico is close to the deepest submarine depression in the North Atlantic Ocean. The Puerto Rico Trench is about 1,090 miles (1,750 km) long and 60 miles (100 km) wide.The deepest point in the Atlantic Ocean, the Milwaukee Depth, lies within the Puerto Rico Trench, at a depth of 8,380 meters in the western end of the trench, about 160 km northwest of Puerto Rico.
The origin of the trench can be traced back to the beginning of the Tertiary period. The Puerto Rico Trench appears to be part of a complex system of sinistral strike-slip faults in the north Caribbean; the trench seems to have been opened continuously for about 70 million years. It is partially filled with sediments.
The length of the above postcard is 300mm long, longer than the ordinary one.
Can you see the folded centre line, I'm not too sure whether the card is designed to be folded.