A

Entry hatch

B

Conning tower (used on Alligator Junior, probably also on Alligator)

C

Diving buoys operated by windlass

D

Emergency ballast cylinders

E

Air hose (longer than shown)

F

Liquid ballast trunks

G

Air purification apparatus containing chemical substances

H

Communications hatch between main and forward compartments

I

Augur, with which to pierce the hulls of enemy vessels, operated by the wheel “N” when engaged with gears “n” (not used)

J

Obstruction-cutting planes (not actually built)

K

Watertight compartment for the divers, who enter by the hatch “H” and fill the compartment with water, allowing them to exit the boat through hatch “k”

M

Regulator to trim the boat

N

Maneuvering wheel

P

Rudder

Q

Pumps for refilling the ballast tanks “F”

R

Hinged oar guards

a

Oar crank handles

b

Rowing benches

c

Deadlights (“illuminating portholes”)

d1

Oars in folded (return) position

d2

Oars in deployed (stroke) position

e

Possible alternative rudder design