Hurricane Maria, the Category 4 storm that devastated Puerto Rico in September 2017, is estimated to have resulted in up to 5,000 fatalities in its aftermath. Maria caused the longest blackout in U.S. history, leaving the entire island of 3.3 million people, including those in hospitals and nursing homes who relied on respirators, without power. >> Read more trending news 'Indirect deaths resulting from worsening of chronic conditions or from delayed medical treatments may not be captured on death certificates,' Harvard University researchers said in a May 2018 study, which contended that the official government death toll of 64 is a 'substantial underestimate.' Related: Study: Puerto Rico death toll 4,600 higher post-Maria According to the study, this makes Hurricane Maria more than twice as deadly as Hurricane Katrina. Following the Harvard report, more than 400 pairs of empty shoes were placed outside the capital building in San Juan, part of a growing memorial to the hundreds of people presumed dead during or in the aftermath of Hurricane Maria. Puerto Rico Gov. Ricardo Rossello told CNN there would be “hell to pay” if officials do not release the updated death toll. Related: Puerto Rico’s empty shoes: Public demands transparency in Hurricane Maria death toll The Category 5 storm hit the U.S. Virgin Islands in mid-September and eventually downgraded to a Category 4, but not before it plowed through Puerto Rico on Sept. 20, 2017, flooded the streets, collapsed homes and left the entire territory without power. Though it’s been several months since the disaster, the U.S. territory could still use your help. Here are some ways to give assistance to Puerto Rico. Related: Volunteer trip to Puerto Rico reveals an island still recovering from Hurricane Maria Support Puerto Rico tourism Tourism makes up 10 percent of Puerto Rico’s gross domestic product. While many resorts and attractions are still struggling to reopen their doors to tourists, about 80 percent of Puerto Rico’s hotels and restaurants officially began serving customers again in April. Many resorts, including the Dorado Beach Resort, which is a Ritz-Carlton Reserve, and the St. Regis Bahia Beach Resort are set to open in October. 'Tourism dollars means that more than 50,000 people will keep their jobs and businesses will keep running,' New York Magazine reported. Airbnb announced in May that, for the next three months, it will be donating any fees from booked trips to recovery organizations, such as All Hands Volunteers. And while you’re in Puerto Rico, be sure to visit the farmers markets, which have suffered from buyer loss due to post-hurricane island flight. Related: Hurricane season is officially here. How much damage will 2018 bring? Your Puerto Rican adventures can do some good, too. 'Rappelling down San Cristobal Canyon supports conservation efforts in the area, a snorkeling trip to a coral reef or mangrove forest might include collecting data on local flora and fauna, and nighttime kayaking to the bioluminescent Mosquito Bay helps fund initiatives to reduce light pollution,' Travel and Leisure reported, adding that most tours are under $15 and can be booked online. You can also plant trees while in the area by signing up with Para La Naturaleza in Cabo Rojo or Barranquitas, or help clean up the coast and help the ecosystems in Manatí. Related: FEMA tells Southeast to prepare for 2018 hurricane season The official Islands of Puerto Rico website says, 'Thank you in advance for your interest in visiting Puerto Rico and supporting our recovery by simply vacationing on the island.' Donate money You can donate funds to a variety of nonprofits and aid organizations working to help Puerto Rico recover. Here are some reputable sites to consider giving monetary donations to: Google.org: Google has committed to matching up to $2 million in donations made between June 8-20 in this campaign heralded by Lin-Manuel Miranda. Your full donation goes directly to one of the charities listed on the official website. Many on the list are also mentioned below. Save the Children: Emergency relief and help for children directly affected by the hurricane. Mercy Corps: Long-term local solutions. Heart to Heart International: Medical care. Hispanic Federation: Provides grants to support more than 70 aid/recovery nonprofits in Puerto Rico. Project HOPE: Medical care. Water Mission: Safe and clean water system restoration. Direct Relief: Health care safety net. First Book: Books and educational resources for children affected. Global Giving: Emergency supplies plus long-term recovery assistance. Habitat for Humanity: Rebuilding and repair. Mission 500: Security company working to serve communities in crisis; holding service trip in the fall. UNICEF: Emergency relief and help for children affected. Amigos de Los Animales: Animal rescue. All Hands: Structural recovery. Charity Navigator can be used to learn more about the organizations before donating. Note that sending money via text message may seem convenient, but according to The Associated Press, that’s not the case. Charities often have to wait on phone companies to release the money. Related: How dangerous is a hurricane? Understanding hurricane categories Volunteer Connect Relief: Food distribution and home reconstruction. Join Mission 500: Security industry professionals interested in assisting families during a service trip from Oct. 31 to Nov. 4. All Hands: Gutting, mucking, debris removal, mold sanitations, cement roofing via computer-generated imagery. Two-week volunteer commitments in Barranquitas and Yabucoa available. Para La Naturaleza: Cleaning and taking care of ecological gardens; helping endangered species. Visit Rico: Farming, agriculture experts . Amigos de los Animales: Help local animal shelters find homes for abandoned cats and dogs. Volunteers can also help clean shelters and photograph animals for the organization’s website. Instituto Nueva Escuela: Help paint schools, repair playgrounds and mentor children affected by school closings and budget cuts post-Maria. Americas for Conservation and the Arts: Social media experts, digital and web-proficient workers to help with volunteer coordination. Chef José Andrés’s World Central Kitchen: Help cook and package fresh meals from one of the #ChefsForPuertoRico kitchens to deliver to the territory’s recovering communities. Explora PR: Adventure travel company with internship and volunteer opportunities geared toward outreach, summer camps, camps for children with autism spectrum disorder and more. Vamonos: Student-focused tour operator with volunteer opportunities related to service in orphanages, foster homes, soup kitchens, construction, environment, schools and more.