Star Trek: 10 Things You Didn't Know About Warp Drive
3. Salamander Speed
In the 24th century, the Warp 10 barrier was redesignated to become infinite velocity, which meant that in theory, no ship should be able to break this barrier. This was tested on a number of occasions. First, the Enterprise-D traveled at speeds that neared warp 10 when both the Traveler and Kosinsky came aboard the ship. The Traveler's modifications allowed the ship to reach galaxy M-33.
Commander Riker and Captain Picard theorized that breaking the warp 10 barrier would allow a ship to travel back in time which, according to them, was how the shuttlecraft El Baz had managed such a feat the following year.
The most significant experiment on reaching warp 10 occurred in the Delta Quadrant. Thanks to the discovery of an extremely rare form of dilithium, Torres and Paris were able to fit the Shuttlecraft Cochrane with a warp 10 coil. The experiment was a success, with a sting in the tail. While Paris did indeed break the barrier, he then underwent a hyper-evolution which saw him evolve into a giant Salamander. Before reaching his final form, he kidnapped Captain Janeway, taking her on a warp 10 flight.
The experiment was deemed too risky to repeat, even though both officers were returned to their normal forms.