North Korea 2009 Turtle sheetlet of 4

The scuba diver is found on the right border of the sheetlet. The stamp is part of a 4-stamp issue on reptiles, the other 3 stamps feature a chameleon, a crocodile and a cobra. The stamps are released in sheetlets of 4 stamps, and only the turtle sheetlet has a scuba diver on the border. The 4 stamps were also issued in a stamp booklet format, but no diving theme there.