I've done it with Dean Soares as a guided trip in his tour boat. I'm not sure if he's still doing tours but you could stop at Neptune's and ask. If not, he might take you on the smaller fishing boat. It's a fun trip with Dean because he knows where to go and see the flamingos, the conch pile, a wreck or 2. Think we spent about 3 hours with him.

You could also check with Danny, the bone fishing guide. Obviously he normally does fishing trips but might take you out to see the conch mountain.