Guam · Guam · Reef · Lagoon

Piti Bomb Holes

Natural percolation pits in a reef flat, 9 m at their deepest

Piti Bay on Guam's west coast is a marine preserve whose "bomb holes" are not bomb craters at all: they are natural percolation pits where fresh water filters up into the shallow lagoon, cut into a reef flat you can walk out to and reaching only 25 to 30 feet (7.6 to 9.1 m). The largest pit holds the Fish Eye observatory, and an estimated 50 to 200 dives a day fall inside the preserve.

Where it is and how deep

Depths on a shared scale to 40 m (130 ft); dashed lines mark common certification limits.

13.4702° N, 144.7012° EApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.

Benthic habitat map of Piti Bay showing coral, algae and turf cover with a Guam location inset — Piti Bomb Holes — NOAA benthic habitat survey of Piti Bay, showing the coral cover inside the preserve — Piti Bomb Holes, Guam. · National Oceanic and Atmospheric Administration · Public domain

The dive

Entry is from Tepungan Park: you walk or snorkel out along the right-hand side of the pier for about 75 yards (69 m) to reach the holes. They are not craters but natural percolation pits, where fresh water filters up into the shallow lagoon through the reef flat, and they range down only to 25 to 30 feet (7.6 to 9.1 m). The whole dive therefore sits inside the first ten metres, and gas rather than depth decides when it ends.

The largest pit houses the Fish Eye Marine Park observatory, which visitors descend into to look at what has grown in the sinkhole, and helmet divers on surface-supplied air pose for photographs on the bottom nearby. You share the water with their hoses and handlers. Traffic sets the character of the dive: an estimated 50 to 200 dives a day fall within a single 0.25-hectare section of the preserve, putting the annual total above 18,000.

Coral damage starts to accumulate rapidly somewhere between 4,000 and 6,000 dives a year, which leaves this patch far past the line, and the numbers climbed sharply after access to Outhouse Beach on Apra Harbor was restricted in 2001. Trim carefully, keep fins clear of the bottom and take nothing out of the water: the whole of Piti Bay is a designated marine preserve.

Marine life and season

The sources we used don't single out particular species here.

Month-by-month season rating for Piti Bomb Holes
Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Good	Good	Good	Good	Good	Good	Good	Good	Good	Good	Good	Good

Season follows Guam: Dry season runs January to June and rainy season July to December; the water stays warm and diving continues all year.

Know before you go

Tourists in Seawalker helmets work the bottom on surface-supplied air in the same water; stay clear of their hoses and their handlers.
An estimated 50 to 200 dives a day fall on one 0.25-hectare patch, far past the 4,000 to 6,000 a year at which coral damage accelerates, so stay off the bottom.

Photos from Piti Bomb Holes

David Burdick / NOAA · Public domain
Gabriel · CC BY 4.0

Dive videos

Guam Dive Sites: Fisheye/ Piti Bomb Holes Marine Preserve · Random Adventure & Interest on YouTube

Questions divers ask

How deep is Piti Bomb Holes?+

The holes reach only 25 to 30 feet (7.6 to 9.1 m) in a shallow reef flat, so the site is dived and snorkelled well inside recreational limits.

Can you dive Piti Bomb Holes from shore?+

Yes. Entry is from Tepungan Park, walking or snorkelling out along the right-hand side of the pier for about 75 yards (69 m) to reach the holes.

Are the Piti bomb holes really bomb craters?+

No. The name is a misnomer. They look like craters in the reef flat but they are natural percolation pits, where fresh water filters up into the shallow lagoon.