Bomba
http://www.antillania.com/Puerto_Rican_Folk_Music.htm
ensembles usually feature three differently pitched drums made from rum barrels, and a single maraca. Two kinds of calls and responses alternate: The singer and chorus respond alternatively to one another, and the high-pitched drum, buliador, alternates with the dancer. Drummer and dancer talk, tease, and challenge each other in their unique language, and when performed well, come together in a sensual duel. 

The bomba is associated with the Northern area of the island around the city of San Juan. The bomba seems to have fewer clear Spanish elements in it than the 'plena' and would seem to be the outcome of cultural expression of a people who knew the African rhythmic tradition but who now had to use Spanish as a common language. The pattern as well as the drums used traditionally to perform it are known as bomba. In addition to these drums some players beat on the side of the drums with small sticks to create a secondary pattern and maracas, or rattles are also employed. Originally performed by singers to the accompaniment of these drums and maracas, the bomba, like the 'plena' has gradually become adapted to the popular dance style of Puerto Rico and its rhythm serves as the basis for new compositions using the 'bomba' rhythm as a basis.

Bomba
www.nyunews.com/news/2004/03/02/UndefinedSection/Bomba.Capoeira.And.BBoying-2390285.shtml

Bomba is an Afro-Puerto Rican music and dance form that dates back to the 17th century. Puerto Rico is the smallest of the Greater Antilles islands in the Caribbean. It shares with the rest of the region a colonial history marked by slavery and the production of sugar, tobacco and coffee. Many of the slaves brought to Puerto Rico to work in the plantations during the slave trade came from West and Central Africa, particularly from the Bakongo nations. Popular music and dances, especially those developed along the sugarcane fields in coastal areas, were highly influenced by African traditions, religious beliefs and expressive forms.

Slaves also came from the French, Dutch and Danish Antilles as part of the slave trade, and freed or runaway slaves also migrated there. These coastal areas became cultural melting pots where people from African, Spanish and European ancestries influenced each other in their singing, dancing and drumming. This is the cultural setting where bomba developed. Because of the cultural juxtapositions of the time, it is common to hear "families" of bomba rhythms in other parts of the Caribbean. Slave owners allowed bomba playing and dancing, probably because they felt it served as entertainment.

Yet it also provided a space where the slaves could communicate safely with each other, maintain cultural and religious traditions and it sometimes served as a planning arena for subversive action. In the 1950s, Ismael Rivera and Rafael Cortijo popularized bomba rhythms in the United States. Bomba became an official folk music and dance form. A number of families, like the Cepedas in Santurce and the Ayalas in Loiza, have kept the tradition throughout the years, teaching and performing. Bomba is still danced in community settings in Loiza during the Fiestas de Santiago Apostol. Since the 1990s, bombazos have been organized both in Puerto Rico and New York City. The dance form is characterized by a rhythmic dialogue where the dancer, who is improvising, executes steps that the lead drummer must try to match simultaneously.