So for the monolingual, "Bahia de Guaymas" means "Guaymas Bay." Don't walk in expecting your typical Mexican steak fajitas, because unless you're coming for lunch this is a Mexican seafood restaurant. Can't speak for the seafood, but the lunch was great.
Very affordable - no lunch special more than $7. Salsa and chips were fresh and tasty. The meal itself was incredibly filling - I had a huge burrito and the wife had her typical cheese enchiladas. You can get whatever meal you ordered smothered in enchilada sauce for an extra 95 cents. The enchilada sauce is reminiscent of New Mexican chile sauce - sweet and spicy.
Music is a bit loud, I got up and discreetly turned it down at one point. As we left a mariachi band was walking in, sorry we missed out on that but we had to run. Overall the place has a low-key party atmosphere. Give it a shot if you're in the area!