I am flying to Vancouver and staying in a hotel for three days before boarding a cruise ship to Alaska. The cruise ends in Anchorage and I fly home via Seattle to Heathrow the same day. Do I say yes or no to 'in transit' on the ESTA application please?
The "in transit" term usually means that you are taking the same mode of transport in and out. But if you are transferring from a ship to a plane, that's not really transit. So I would suggest "No".
For the purposes of ESTA, it doesn't really matter either way, since you would get the same kind of entry permission (the Visa Waiver Program) no matter which way you choose. And if you are a UK citizen, it's unlikely to matter at all. Enjoy your trip!