Hi Chis - what kind of stuff do you like to do?
Down on San Diego Bay (where you pretty much are), there is the Maritime Museum which has the tall ship Star of India, the Berkley (ferry) and US/Russian subs you can check out. they also offer a harbor tour on a Pilot boat, which is pretty decent.
The USS Midway aircraft carrier is also down there that you can tour.
You could take a speedboat tour on SD Bay, where you drive your own speedboat.
https://www.speedboatadventures.com/?gclid=CjwKEAiA_p_FBRCRi_mW5Myl4S0SJAAkezZrj3YR9apXII0tVvS2kkT4ElSVa-lfbGvZSH9Gv9AJyBoC4KHw_wcBMight be kind of fun, but you're in a follow the leader kind of setup...
Balboa Park isn't too far from you either. There you'll find the San Diego Zoo, the Ruben H. Fleet Science Center and a variety of museums.
The Fish Market is a nice place to eat - especially if you can sit out on the patio (they also have an enclosed patio right on the water that is nice when the weather isn't...)
Let me know if I can offer any other suggestions!
Erik
Oh, BTW - you're also in micro-brew central so if you're a beer drinker you have countless good options! Do a Google search on San Diego Breweries.