The boat I just purchased has a 1993 Johnson 25hp engine, I know I should replace the water pump (owner says it has never been replaced), change the lower unit fluid, and adjust the carb. Is there anything else this newbie to boat ownership should have checked?

Can the service guys do a compression check on the engine?

Are spark plugs OK?

I am sure there are other things that the guys will suggest.

Impeller, Gas hose and bulb.

Impeller, Gas hose and bulb.

+1 and the fuel filter

Adjust the carb?  I don't think you do that unless it needs it.

And run a fuel additive carb cleaner through it before you adjust it. Its cheap and sometimes it works.

<---not a mechanich

There are 3 things required for an internal combustion engine to work

1. Fuel

2. Air

3. Spark