I'm vacationing in Miami and just learned of the ferry traveling to the Bahamas. I am a US citizen with a valid Missouri driver's license but I did not bring my passport. Could I use my driver's licence instead?

No you can't a few years ago you could have changed policy by be the u.s. government

I think with a valid driver's license you can only do same day travel. Meaning you can only travel and return on the same day. No over night stay.

Birth certificate is required

yes you can use your drivers licence

To travel by boat to bahamas from the US you must present birth certificate with ID if you dont have a passport.