Santa Cruz, officially the Municipality of Santa Cruz,  is a 1st class municipality in the province of Marinduque, Philippines. According to the 2020 census, it has a population of 54,692 people.

The municipality of Santa Cruz in Marinduque is best known for its main attraction, Maniwaya Island. Along with the island, the town also boasts several caves, waterfalls, and historic sites. Among its best spots are the Kawa Kawa Falls, which gets its name from its pan-shaped base.

Santa Cruz is also known as one of the three areas affected by the Marcopper tragedy, a fracture in the drainage tunnel of Marcopper Mining Corporation’s Tapian pit spilled more than 1.6 million cubic meters of toxic mine tailings, flooding villages and poisoning the Boac River.

As early as March 1998, too, then President Fidel Ramos had declared a state of calamity in four Sta. Cruz barangays near Calancan Bay — Botilao, Ipil, Lusok, and Camandugan — due to the high incidence of heavy-metal poisoning among the children there.

A data report in 2008 showed that in these same barangays, the prevalence rates of illnesses considered to be symptoms of heavy-metal poisoning far outpace national figures. In fact, the four barangays have influenza and hypertension prevalence rates that are some eight times that at national level — 4,283.96 per 100,000 population for influenza and 4,079.96 for hypertension, compared to the national prevalence rates of 435 and 522.8, respectively.