i got another suggestion a light tank wich might be a reality

The Soviet Amphibious Light tank PT-76 it's got fairly good armour and not a too bad gun and it can swim.
but cause it's an amphibian tank it's armor really lets it down so it's only good for surprise attacks, Heavy Recon, Ambushes and river patrol as a temporary PBR
her's some facts about itType Amphibious Light Tank
Place of origin Soviet Union
Service history
In service 16 August 1952–present
Production history
Designer N. Shashmurin and Zh.Y. Kotin
Designed 1949–51
Manufacturer VTZ, Kirov Factory
Produced 1953–69
Number built Around 12,000[1]
Specifications (PT-76 model 1)
Weight 14.6 tonnes
Length 6.91 m (hull)
Width 3.15 m
Height 2.325 m
Crew 3 (driver, commander, loader)
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Armour 20 mm as you see it's not like an overlord tank with god armour
Primary
armament 76,2 mm D-56T rifled tank gun (40 rds.)
Secondary
armament 7.62 mm SGMT coax machine gun (1,000 rds.)
Engine 6-cyl. diesel
240 hp (179 kW)
Power/weight 16.4 hp/tonne
Suspension torsion-bar
Ground clearance 370 mm
Fuel capacity 250 l
Operational
range 370–400 km, 480–510 km with external fuel
Speed 44 km/h (27 mph), 10.2 km/h (6.3 mph) swimming

this is the waterjets one covered by the protection plates that makes the Propulsionary thrust for the PT-76 on the water.
this tank was used in the cold war and is still being used today.