Balboa got its name from the Balboa Peninsula at Newport Beach, situated on the coast about 40 miles south of Los Angeles in California. The dance was first done at the Beach Pavilion and then latterly at the famous Rendezvous Ballroom.
There are two different forms of Balboa, known as 'pure' Balboa and Bal-Swing. Balboa is danced in closed hold and evolved in dance halls where space was limited. Pure Balboa is characterised by a fairly upright posture with both partners standing close to one another. You don't break away from your partner. In contrast, Bal-Swing incorporates spins, turns, dips and tricks.
Have a look at a couple of clips :