The Pytheas was a Federation Starfleet class H shuttlecraft assigned to the USS Enterprise-B in the 2310s.
In the year 2319, Lieutenant Verant piloted the Pytheas to a trans-dimensional portal on the surface of Rejarris II, through which Captain Demora Sulu and Ensigns Hawkins Young and Galatea Kostas had been stranded. Verant was transported back to the Enterprise before the shuttle reached the portal, and Pytheas continued through it on autopilot. Pytheas was then used by Sulu to explore the planet while Kostas cared for the injured Young. (TLE novel: One Constant Star)