Recreational Guidance


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Why do we need reef safe tourism?

Studies show recreational use:

  • Increases corals’ susceptibility to pathogens and predation, due to decrease in physiology as a result of direct physical damage by divers (Hawkins et al. 1999)
  • Decreases coral cover (Hawkins and Roberts 1993, Hasler and Ott 2008)
  • Increases coral damage (Allison 1996, Au et al. 2014, Hawkins and Roberts 1993, Di Franco 2009, Hasler and Ott 2008, Guzner et al. 2010)
  • Disturbs fish behavior and communities (Albuquerque 2015, Di Franco 2013)
  • Increases prevalence of coral disease, in some cases up to 3 times greater (Guzner et al. 2010, Lamb et al. 2014)
  • Slows coral growth rates (Guzner et al. 2010)
  • Shifts species dynamics, upsetting the balance and ecological function of the ecosystem (Hawkins et al. 1999)
  • Increases susceptibility to predation (Guzner et al. 2010)
  • Increase tissue abrasion (Hawkins et al. 1999)

Coral Reefs are living animals. They are slow-growing, fragile, and can break easily when walked on, kicked, or touched. Corals are sensitive to human interaction so we ask that everyone swimming on or near coral reefs are aware of their surroundings and do not disturb marine life. Please help us protect our coral reefs for generations to come!


  • Please avoid contact. Do not touch, kick, or stand on coral.
  • Help keep our island and oceans clean. Take all trash with you, and reduce your use of plastics.
  • Watch your step and only rest in the sand. Please avoid standing on coral reefs or seagrasses.
  • Wear a life jacket or use a floatation device so you do not need to stand on the reef.
  • Coral is fragile and breaks easily. Baby corals are not visible to the eye and can be killed by walking on reefs, even if you cannot see the coral.
  • Watch your fins when snorkeling and do not kick up sand on the reef.
  • Feeding fish is harmful to marine life. Fish feeding disrupts the balance of a healthy reef and may make fish more aggressive. Keep wildlife wild.
  • Please do not chase marine animals and avoid blocking their path.
  • Look but do not touch animals. Handling some marine life can be dangerous to people and to the animal.
  • Look for entry and exit pathways and avoid walking through seagrass. At Piti Bomb Holes Marine Preserve, please only enter and exit directly next to the observatory pier.
  • Use reef safe sunscreen. Choose mineral-based sunscreen.
  • Respect fishing regulations and marine preserve rules.
  • It is illegal to take corals, shells, sand, or anything else from marine preserves unless permitted by law.


  • Be aware and look for posted signs about rip currents before entering the water. If you feel you are caught in a rip current, do not fight or swim against the current. Swim parallel to shore and then swim back in away from the outgoing current.
  • Check local advisories before entering the water.
  • For surf, winds, and tide conditions DIAL 211 or visit the National Weather Service website at
  • For beach advisories, visit
  • Check lifeguard tower for flag warnings. Do not swim under a red flag.
  • Always swim with a buddy.
  • Use a floatation device, coral is sharp so please stay off the bottom.
  • Guam Fire Department DIAL 911
  • Boating/Diving Emergency: U.S. Coast Guard DIAL 355-4821



Guam has 5 marine preserves that have restricted fishing. It is illegal to take any shells, coral, sand, or other marine life from these areas. Please look for marine preserve signs at each site for fishing rules:

  • Tumon Bay Marine Preserve in Tumon/Tamuning
  • Piti Bomb Holes Marine Preserve in Asan/Piti
  • Sasa Bay Marine Preserve in Apra Harbor
  • Achang Reef Flat Marine Preserve in Merizo
  • Pati Point Marine Preserve in Yigo

Guam marine preserves



  • LOOK OUT for dive flags and stay away. Keep a safe distance (200 ft./60 m) from all swimmers, divers, and snorkelers.
  • Waves from motorized watercraft increase erosion of the land. Please keep away from the shoreline and minimize your speed near the coastline.
  • Please avoid coral reefs, seagrasses, and marine life.


  • It is illegal to chase, harass, or corral marine mammals. Please do not separate individuals from their pod.
  • When dolphin or whale watching, the boat should remain parallel to the movement of the animals and always give the right away. Please maintain a safe distance of 50 yards minimum.
  • Dolphins and whales are sensitive to sound. Please minimize noise disturbance.
  • Do not feed fish, dolphins, turtles, or other marine life. Keep wildlife wild.
  • Do not throw food scraps overboard. Fish feeding alters animal behavior.


Picasso Triggerfish
Picasso triggerfish’ mouths are built to crush because they eat crustaceans, urchins, and other hard-shelled animals. They build their nests in the sand and can be very territorial. Triggerfish may become aggressive if you come too close, so always keep a safe distance from any wildlife while swimming and walking in the sand.
The dolphins most commonly found in Guam’s waters are spinner dolphins, named for their famous acrobatic performances. They can be seen jumping and spinning out of the water, putting on a great show for boaters. Spinner dolphins frequently hunt with yellowfin tuna, so they are vulnerable to impacts of fishing such as entanglement. Dolphins, also known as tuninos in CHamoru, are protected by federal law. It is illegal to chase, feed, touch, or harass them. Please maintain a respectful distance from dolphins and do not block their path. Help us keep wildlife wild.

Merizo’s original village name is Malesso’, derived from the CHamoru word lesso’, a juvenile stage in the growth of rabbitfish. Juvenile rabbitfish, or mañahak in CHamoru, are a local delicacy and significant to Guam’s cultural heritage. Mañåhak run up along the shoreline of reef flats each year in what is locally known as the “mañahak runs” . Fishermen their talaya, or cast nets, year after year for mañahak runs.

Sea Turtles
Green sea turtles, or Hagaan, are important to CHamoru culture. Haggan was traditionally eaten on special occasions, and Chamorros used their shells for jewelry. Bones were also used to make tools. Green sea turtles get their name from the color of their fat, which is believed to be green because of their herbivorous diet. They graze on seagrasses and algae from the reef. Green sea turtles are endangered so touching, chasing, harassing, and feeding is illegal (IUCN/NMFS/USFWS).

Coral Bleaching
Many people think coral is a rock or plant, but it is actually an animal. Corals rely on tiny algae living inside them, called zooxanthellae, to provide them with food through photosynthesis, and in return they provide the algae with shelter. When the waters become too warm the coral may eject its algae and turn white. This is called coral bleaching. Coral bleaching can be deadly to coral reefs if the water does not cool back down. Because of this and other impacts, Guam lost 1/3 of its shallow corals from 2013-2017.

Piti Bomb Holes
The famous “bomb holes” in Piti Bomb Holes Marine Preserve are actually natural springs where freshwater seeps from the ground and reaches the reef at 25-30 ft. Two species of mollusks and one species of sea urchin are found in these holes that are not found anywhere else in the world. Piti Bomb Holes has the most diverse habitat of all marine preserves in Guam (Source: NOAA).