Editing Operation Sea Lion (section)

=== Panzers ashore ===
Providing armour support for the initial wave of assault troops was a critical concern for Sea Lion planners, and much effort was devoted to finding practical ways of rapidly getting tanks onto the invasion beaches in support of the first echelon. Though the Type A barges could disembark several medium tanks onto an open beach, this could be accomplished only once the tide had fallen further and the barges were firmly grounded along their full length; otherwise, a leading tank might topple off an unsteady ramp and block those behind from deployment. The time needed for assembling the external ramps also meant that both the tanks and the ramp assembly crews would be exposed to close-quarter enemy fire for a considerable time. A safer and faster method was needed, and the Germans eventually settled on providing some tanks with floats and making others fully submersible.  It was nevertheless recognised that a high proportion of these specialised tanks might be expected not to make it off the beach.

==== ''Schwimmpanzer'' ====
The ''Schwimmpanzer'' II Panzer II, at 8.9 tons, was light enough to float with the attachment of long rectangular buoyancy boxes on each side of the tank's hull. The boxes were machined from aluminium stock and filled with Kapok sacks for added buoyancy. Motive power came from the tank's own tracks which were connected by rods to a propeller shaft running through each float. The ''Schwimmpanzer'' II could make 5.7&nbsp;km/h in the water. An inflatable rubber hose around the turret ring created a waterproof seal between the hull and turret. The tank's 2&nbsp;cm gun and coaxial machinegun were kept operational and could be fired while the tank was still making its way ashore. Because of the great width of the pontoons, ''Schwimmpanzer'' IIs were to be deployed from specially-modified Type C landing barges, from which they could be launched directly into open water from a large hatch cut into the stern. The Germans converted 52 of these tanks to amphibious use prior to Sea Lion's cancellation.<ref name=Schenk113>Schenk, p. 113</ref>

==== ''Tauchpanzer'' ====
[[File:Bundesarchiv Bild 101II-MW-5674-45, Übungen mit Panzer III für Unternehmen Seelöwe.jpg|thumb|left|A [[Panzer III]] ''Tauchpanzer'' under test (1940); the [[crane ship]] {{SMS|Viper|1876|2}}, which was to support Tauchpanzer operations, is in the background]]
The ''Tauchpanzer'' or [[Deep fording|deep-wading]] tank (also referred to as the ''U-Panzer'' or ''Unterwasser Panzer'') was a standard [[Panzer III]] or [[Panzer IV]] medium tank with its hull made completely waterproof by sealing all sighting ports, hatches and air intakes with tape or caulk. The gap between the turret and hull was sealed with an inflatable hose while the main gun mantlet, commander's cupola and radio operator's machine gun were given special rubber coverings. Once the tank reached the shore, all covers and seals could be blown off via explosive cables, enabling normal combat operation.<ref name=Schenk111>Schenk, p. 111</ref>

Fresh air for both the crew and engine was drawn into the tank via an 18&nbsp;m long rubber hose to which a float was attached to keep one end above the water's surface. A radio antenna was also attached to the float to provide communication between the tank crew and the transport barge. The tank's engine was converted to be cooled with seawater, and the exhaust pipes were fitted with overpressure valves. Any water seeping into the tank's hull could be expelled by an internal [[bilge]] pump. Navigation underwater was accomplished using a directional [[gyrocompass]] or by following instructions radioed from the transport barge.<ref name="Schenk111" />

Experiments conducted at the end of June and early July at Schilling, near [[Wilhelmshaven]], showed that the submersible tanks functioned best when they were kept moving along the seabed as, if halted for any reason, they tended to sink into the seabed and remain stuck there. Obstacles such as underwater trenches or large rocks tended to stop the tanks in their tracks, and it was decided for this reason that they should be landed at high tide so that any mired tanks could be retrieved at low tide. Submersible tanks could operate in water up to a depth of {{convert|15|m|ft|0}}.<ref name=Schenk110-111>Schenk, pp. 110–11</ref>

The ''Kriegsmarine'' initially expected to use 50 specially-converted motor coasters to transport the submersible tanks, but testing with the coaster ''Germania'' showed this to be impractical. This was due to the ballast needed to offset the weight of the tanks, and the requirement that the coasters be grounded to prevent them from capsizing as the tanks were transferred by crane onto the vessel's wooden side ramps. These difficulties led to development of the Type B barge.<ref name="Schenk110-111" />

By the end of August the Germans had converted 160 Panzer IIIs, 42 Panzer IVs, and 52 Panzer IIs to amphibious use. This gave them a paper strength of 254 machines, about an equivalent number to those that would otherwise have been allocated to an armoured division. The tanks were divided into four battalions or detachments labelled ''Panzer-Abteilung'' A, B, C and D. They were to carry sufficient fuel and ammunition for a combat radius of 200&nbsp;km.<ref name=Evans121>Evans, p. 121</ref>