Cruise from Amsterdam to Haarlem?

You asked a similar question a couple of weeks ago. https://community.ricksteves.com/travel-forum/netherlands/day-cruise-advice
I’m afraid the answer is still the same, such a cruise does not exist.

And it's about a 15/20 minute easy train ride from Amsterdam to Haarlem.

OK, thanks. Does Uber work smoothly between Haarlem and Amsterdam?

Uber or Bolt from Amsterdam to Haarlem, no issues. Haarlem to Amsterdam, there may be fewer Ubers available due to lower demand in Haarlem due the compactness of the (mostly pedestrian) city center and most would travel by train to Amsterdam due to the relatively high price (compared to the train).

https://9292.nl/en will give you an idea of the travel time and costs when taking the train (or bus depending where you are in Amsterdam). You can enter Amsterdam and Haarlem (vice versa) in the Uber app to get the local Uber prices to compare.

there are real taxis in Haarlem too.

Nigel, good call -out! Taxi stands are at the train station and, in the weekend evenings, I see them in front of the city hall on the Grote Markt. Restaurants and bars can call a taxi for you, of course, which often is more effective to find one.

I am inclined to stay in Amsterdam to visit Amsterdam. (5 visits) You may be disappointed in the cost of taking taxis between two cities, including the likely "cost" of returning empty. This is not like a one mile trip home from a bar after work in the US.

Haarlem is basically a suburb of Amsterdam. If you are coming from a cruise that docks in Amsterdam then take the train. Maybe a ten minute walk at most from the further dock to the train station or two minutes if you get lucky with a dock just behind the train station. The train ride to Haarlem is another 10 to 15 minute ride. I know a bus is available but we have only taken the train between the two.