Riding around in the Goose
How about this great early 1941 image of a Coast Guard airman hanging out of the hatch observation window of a seaplane, M1928 Thompson at hand.
Official caption: “Inasmuch as the Coast Guard is primarily a maritime law enforcement agency, the Aviation Arm is often called upon to do such jobs as aiding in the location of smuggling vessels or the capturing of escaped convicts.”
National Archives Identifier 205576693
Judging from the rivets and the window pattern of the above image, which is surely posed on the ground, the aircraft seems to be a Grumman JRF-5G (G-38) Goose amphibian, of which the service acquired 24 in early 1941 as a follow-up to the smaller JRF-2/3 (G-21), which did not have the same window in the hatch.
As noted by the CG Aviation History Assoc:
Prior to World War II these aircraft carried out search and rescue as well as aerial mapping flights and participated in the Coast Guard’s contribution to the enforcement of the Neutrality Patrol. During the war, the JRFs conducted search and rescue operations, transported supplies and personnel, and were utilized for ASW operations. Depth Charges or Bombs were carried externally under the wing.
Most of the remaining Coast Guard’s JRF-2/3s were disposed of shortly after the end of World War II while many of the JRF-5Gs remained in service with the Coast Guard until 1954.
USCG JRF-5G No. 4792 aboard Coast Guard Air Station San Francisco, September 1951, via Wikicommons. Note the back hatch and rivet pattern.
laststandonzombieisland 
Neat post and very informative – thanks! An uncle was a Goose Crew Chief in Panama 1938-1941. He and his fellow crew even survived a Dec 1939 open ocean crash in one!