World's Biggest Amphibious Airplane

This is the Russian Albatros. Cetainly not the first jet seaplane, but very unique and capable:

This is the world's only turbojet that can take off and land both on water and at a conventional airport. It can perform numerous tasks: search for SSBNs (ballistic missile submarines), rescue merchant vessels and warships in distress, and even quench forest fires. I'll describe its capabilities later. Let's first talk about the A-40 amphibian itself.
Gennady Panatov, one of its designers, told me that the Albatross, at 86 metric tons, is also the world's biggest amphibious airplane. It was tested in 1990, and was nearly adopted, but was not produced en masse for reasons we'll discuss later...

Apart from its smart, appealing design, the Albatros has unique combat capabilities. It is primarily a military aircraft, a kind of submarine hunter, which was once part of the national anti-submarine defense. It can fly 2,000 km out to sea (this is its range; as the crow flies it can cover a distance of 5,500 km); barrage a suspected nuclear submarine deployment area for five to eight hours (up to 12 hours with refueling); descend on water like its living namesake, the world's biggest bird; turn off the engines and listen to traffic noise; and conduct other "search operations," to use a military term. It can track a submarine, pinpoint its location with indicator buoys (or surround it with red flags, as if it were a wolf), follow it all the way, take off without losing touch with it, and then land again if it stays deep for a long time or lies on the seabed.

How about this as a P-3 Orion replacement!