AirHint found the following cheapest return flights from Knoxville (TYS) to San Juan (SJU) in December 2025 (see full year).
Return flights
| 23 Dec - 07 Jan | Allegiant Air | ||
| 31 Dec - 04 Jan | Allegiant Air |
Also check the deals for one-way flights from Knoxville to San Juan in December.
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