If you're in Santo Domingo you must go and see a baseball game.
The local teams are Licey and Escogido and they both play at Estadio Quisqueya. Dominican baseball is of a high standard, and many players also play in the Major League in USA.
There's a fantastic atmosphere in the stadium during the match: Drums, singing, dancing...
Games can be sold out (especially Licey against Aquilas (from Santiago)), so remember to check for available tickets before you go.
The Quisqueya Stadium is the biggest baseball stadium in Santo Domingo and the home of the 2 city teams Tigres del Licey (Licey tigers) and Leones del Escogido (Escogido lions).
Licey was the first baseball team formed in the country and have won most of the league tournaments (if they haven't then the Cibao team Aguilas has - at the moment I don't follow who's won the most tournaments). Escogido was the team created by the dictator Trujillo.
The Dominican baseball season goes between late October and late January and during these months the country gets divided by colors (symbolizing the colors of the teams). Of course this we mean in a not so serious way. The season ends with a Caribbean tournament (Serie del Caribe) in the first week of February.
Tickets for games Licey-Aguilas and Licey-Escogido can be sold out quickly and the lines to get in to the stadium can be long, so be there in good time.
A little OT: when there's no baseball this stadium might be used for (music) concerts.
Equipment: Come as you are and enjoy yourself.
Do you like bowling? Then Sebelén Bowling Center is the place to go. It's 2 levels with 48 bowling lanes and some arcade machines. If hunger attacks, there's a cafeteria and Split café/sport bar and billiards with 2 billiard/pool tables.
And for those who want to learn how to (properly) bowl, there's a bowling school (La Escuelita) for ages 6 and up. Saturdays starting at 10am is the kids' school and Monday-Friday between 5pm and 7pm is the adults' school.
Equipment: You rent your shoes there. I believe you can bring your own equipment if you have it.