The company also launched a sweepstakes that will award a free cruise for two on the maiden voyage to the Dominican Republic.
Fathom’s holiday 'D.I.B.S.' (Deep Impact. Big Savings.) offer is available through February.
Travelers who book a trip to the Dominican Republic can save up to $400 per person. Per person savings are $100 for an inside room, $200 for an ocean-view room, $300 in a balcony accommodation and $400 in a suite.
Plus, the third and fourth travelers in a family or group sale free.
The deposit has been reduced 50%, with $150 due at initial booking.
For Cuba sailings—which still await Cuban authorities' approval, Fathom also cut the deposit by 50%, to $300.
In addition, Cuba travelers can get a $50 on-board credit for booking an inside or ocean-view room and a $100 credit for booking a balcony or suite accommodation.
The sweepstakes gives the chance to win an all-inclusive cruise for two on Fathom's April maiden voyage to the Dominican Republic, in an ocean-view room. The cruise is valued at $3,240.
Sweepstakes details are here.