The submarine's voyage to Argentina led to legends, apocryphal stories and conspiracy theories that it and U-530 had transported escaping Nazi leaders (such as Adolf Hitler) and/or Nazi gold to South America, that it had made a secret voyage to Antarctica, and even that it sank the Brazilian cruiser Bahia as the last act of the Battle of the Atlantic.

U-977 was powered by two Germaniawerft F46 four-stroke, six-cylinder supercharged diesel engines while surfaced and two Brown, Boveri & Cie GG UB 720/8 double-acting electric motors while submerged.

According to the Navy report, the submarine stopped in the Cape Verde Islands for a short break, then completed the trip traveling on the surface using one engine.

Crossing the equator on 23 July, she arrived in Mar del Plata, Argentina on 17 August after 99 days at sea from Bergen and a voyage of 14,157 km (7,644 nmi, 8,797 mi).

These points agree with Schäffer's report that he stopped at Cape Verde Islands for a short break and crossed the equator on 23 or 24 July 1945.

Schäffer said that, after the short Cape Verde break, they completed the rest of the trip to Mar del Plata alternately on the surface and submerged.

A documentary film U-977 - 66 Days Under Water directed by Nadine Poulain, Schäffer's granddaughter, was in the final stages of production in 2014.