The fine print:

$300 per person airfare deposit is due to Avalon Waterways 2 weeks after reservation/$250 per person deposit is made.  Avalon Waterways will contact guests once stateroom is reserved.

Book a select 2022 Avalon Waterways Europe river cruise to receive $399 round-trip economy class trans-Atlantic air from ATL, BOS, CHI (MDW, ORD) CHS, CLE, CLT, DEN, DFW, DTW, IAH, LAX, MCI, MIA, MCO, MSP, NYC (EWR, JFK, LGA), OKC, PDX, PHL, PHX, PIT, RDU, SAN, SEA, SFO, SLC, STL, TPA, WAS (BWI, DCA, IAD). Other gateway cities available from $200 to $1,075/person additional (inclusive of taxes/fees). $399 air offer is based on lowest-priced economy class Flex airfare available for booking at time of reservation and scheduled to coincide with cruise itinerary; pre-assigned airline seats are limited and may not be available on all air segments. Alternate schedules may be available at an additional cost. In lieu of $399 Air a different promotion can be offered by calling Avalon Waterways. Quotes available online, calling Avalon Waterways or by calling a Travel Professional. Limited to new bookings for US originating travelers and economy class Flex air tickets; must be booked & under deposit between January 4, 2022 and May 30, 2022 for select cruises in 2022. A $550 non-refundable deposit is due at time of booking. Flight deviations are allowed when purchasing extra nights through Avalon Waterways only. Offer does not apply to instant purchase air, custom, or charters. Groups of 8 passengers or more don't qualify for this offer. Please call for Group promotion options. Offer is combinable with select $$ off promotions, Welcome Back Credit, Peace of Mind Credit, and select account specific offers. Promotional discounts do not carry forward on voluntarily changed air bookings; other promotions at time of change may be available. Once ticketed, air reservations subject to change/cancellation penalties of between $300 per ticket and 100% of ticket value. Changes to ticketed air reservations (including itineraries involving free round-trip trans-Atlantic air) also subject to airfare differentials between originally ticketed air itinerary and re-ticketed air itinerary. Additional airline baggage fees may apply; visit www.iflybags.com for details. Air schedules are available approximately 330 days prior to return travel date. Flight schedules, routings and air carriers are at the discretion of Globus family of brands. Additional restrictions apply; see Travel Terms for details. Air tickets are non-commissionable. Offer is capacity controlled and may be withdrawn at any time. Offer available from participating GFOB offices only. CST#2017032-20. PRMYWL