Alberto de Jesús Mercado (born 1958), better known as Tito Kayak, is an activist from Jayuya, Puerto Rico, and founder of the Puerto Rican environmental group, . The organization utilizes a dual approach, which they call "manatiburón (manatee/shark)", which Kayak describes as a combination of "peaceful and simple ways to fulfill our environmental ideals" (like the manatee), and the more “revolutionary approach" (like the shark), which is "only used when we are prohibited from working peacefully towards our goals of improving the environment." Kayak is best known for his activism against the damaging environmental effect of the U.S. Navy presence on Vieques.