Viator’s Worry Free Guarantee works in two ways:

If you, through no fault or action of your own, are not returned to the ship in time to board, we will arrange the necessary transport to the next port-of-call. The policy is void in instances where delay is caused by your own actions and/or you have deviated from the Viator activity or tour itinerary. You must supply Viator with correct arrival and departure ship information and ensure there is enough time (minimum 2 hours) between the tour end time and the ship departure time. You must contact Viator directly to request next port-of-call transportation arrangements as customers cannot book their own travel. Viator will select and book travel for you to the next port of call (not to exceed US$1,000 per person).
In addition, if your ship misses a port of call or is delayed beyond the commencement time of your Worry-free Shore Excursion, simply contact Viator within 14 days. Pending verification of the ship's actual itinerary, we will issue you a refund.

Note: This policy only applies to tours marked as having the Worry Free Guarantee and does not apply to excursions with private tour guides booked through Viator's Private Guide program.

Please click here https://www.viator.com/support/termsAndConditions#prodAmend for more detailed terms and conditions of Viator's Worry Free Shore Excursion Guarantee.