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Gamat Bay

📍 Bali, Indonesia

Reef Manta Ray (Mobula alfredi) — recorded at Gamat Bay

Gamat Bay is a dive site in Bali, Indonesia. It lies within the Nusa Penida Marine Protected Area. The sea floor at the site position lies at about 29 meters. Currents typically run at 2.6 km/h and reach 4.2 km/h on the strongest days. Water temperatures range from 27°C in September to 30°C in December. The typical daily tidal range is about 1.5 m. Species recorded in the area include Barred Filefish, Reef Manta Ray, Boivin's cowrie, Sixline Wrasse and Raccoon Butterflyfish.

Dive Conditions

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Seabed Depth
29m
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Current
2.6 km/h (4.2)
🌡️
Water Temp
27–30 °C

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Typical Current 2.6 km/h (up to 4.2)
Seabed Depth 29 m
Water Temperature 27–30 °C
Tidal Range 1.5 m (typical daily)
GPS -8.6991°, 115.4669°

Data sources: currents and water temperature from Open-Meteo Marine (CC BY 4.0), hourly model values 2024; seabed depth from the GEBCO 2020 Grid, sampled at the site coordinates (grid resolution about 450 m). Tidal range is the median daily range of modelled sea level from Open-Meteo Marine, hourly values 2024. Protected area boundary from OpenStreetMap contributors (ODbL). Species observations from iNaturalist, checked against the World Register of Marine Species.

Conditions at Gamat Bay through the year

Sea surface temperature at the site coordinates, averaged per month from hourly model values for 2024. The water is warmest in December at about 30 °C and coolest in September at about 27 °C, a spread of 2.7 degrees across the year.

Monthly sea surface temperature at Gamat Bay (°C)
JanFebMarAprMayJunJulAugSepOctNovDec
29.3 29.6 29.7 29.0 28.3 28.2 27.6 27.5 27.1 27.5 29.1 29.8

Ocean current at the site runs at a typical 2.6 km/h. In the strongest tenth of the hours modelled for 2024 it reaches 4.2 km/h, which is when entries are normally timed to slack water at the turn of the tide.

The tide moves the water level by a median 1.5 m over a day, and by up to 2.1 m on the largest days of the month. That range drives how much water is exchanged over the reef and when the current turns.

In the open sea off Gamat Bay, the highest wave of the day exceeded 1.5 m on 3.7 % of days between 2015 and 2024. The roughest month was July (10 % of days), the calmest November (0 %).

Share of days with waves above 1.5 m, open sea near Gamat Bay (%, 2015–2024)
JanFebMarAprMayJunJulAugSepOctNovDec
2131371084201

The seabed directly under the site coordinates sits at about 29 m. This is a bathymetry grid value with a cell size of roughly 450 m, so it describes the depth of the area rather than the deepest point a dive can reach.

Gamat Bay lies inside Nusa Penida Marine Protected Area. Protected areas can carry their own rules on entry fees, permits, anchoring and fishing; check the current rules with a local operator before you dive.

How Gamat Bay compares

These comparisons use only the measured values above, set against the 376 dive sites published on findadive.com. A percentage shows the share of other sites with a lower (or higher) value, so it reads the same way wherever the site is. Gamat Bay sits with its mean water temperature in the bottom tenth and its coolest-month water temperature in the bottom tenth of all listed sites.

Gamat Bay compared with all listed sites and with Bali
MeasureThis siteCompared with all sitesMedian in Bali
Mean water temperature28.6 °Ccooler than 90 % of the other 375 sites29.1 °C (99 sites)
Water temperature in the coolest month27.1 °Ccooler than 90 % of the other 375 sites27.8 °C (99 sites)
Typical current2.6 km/hstronger than 78 % of the other 375 sites3.2 km/h (99 sites)
Current in the strongest 10 % of hours4.2 km/hstronger than 73 % of the other 375 sites5.7 km/h (99 sites)
Median daily tidal range1.5 mlarger than 60 % of the other 375 sites1.5 m (99 sites)

Water temperature, current and tide from Open-Meteo Marine (CC BY 4.0), hourly model values for 2024 at -8.6991°, 115.4669°. Seabed depth from the GEBCO 2020 Grid. Protected area boundary from OpenStreetMap contributors (ODbL). Wave statistics from ERA5-Ocean via Open-Meteo Marine (contains modified Copernicus Climate Change Service information 2015–2024), daily maximum wave height on a 0.5° grid; land shelter tested against Natural Earth coastlines.

Marine life recorded at this site

Research-grade observations from iNaturalist within about 12 km of these coordinates.

Barred Filefish (Cantherhines dumerilii)
Barred Filefish Cantherhines dumerilii A large, deep-bodied filefish with a barred pattern of dark vertical lines on a pale background. It has a small, upturned mouth and a single dorsal spine.to 38 cm · 3-40 m · by dayouter reef slopes and channels, often near coral or rubbleOften solitary. Moves slowly with undulating fins; approach gently to avoid startling it. (c) Nick Tobler (Cowturtle), some rights reserved (CC BY) · observation
Reef Manta Ray (Mobula alfredi)
Reef Manta Ray Mobula alfredi A large, flat ray with a dark grey to black upper side and white underside, often with distinctive shoulder patches. It swims by flapping its wing-like pectoral fins.to 5.5 m wingspan · surface to 30 m · day and nightnear coral reefs, cleaning stations, and channelsObserve from a distance at cleaning stations; mantas will circle the area repeatedly, allowing for extended viewing. no rights reserved · CC0 · observation
Boivin's cowrie (Naria boivinii)
Boivin's cowrie Naria boivinii A small, glossy cowrie with a pale base colour and a pattern of irregular brown spots and blotches, often with a darker dorsal line.to 3 cm · 5-25 m · at nightunder coral rubble and in reef crevicesLook for its mantle, which is a mottled brown tissue covering the shell when the animal is active. (c) River Ahlquist, some rights reserved (CC BY) · observation
Sixline Wrasse (Pseudocheilinus hexataenia)
Sixline Wrasse Pseudocheilinus hexataenia A small, slender wrasse with six horizontal blue lines on an orange body, constantly darting among coral branches.to 10 cm · 2-35 m · by daydense coral branches and rubble on outer reef slopesLook for its quick, jerky movements in coral thickets; it often retreats into crevices if approached. (c) Nick Tobler (Cowturtle), some rights reserved (CC BY) · observation
Raccoon Butterflyfish (Chaetodon lunula)
Raccoon Butterflyfish Chaetodon lunula A butterflyfish with a yellow-orange body, a black mask across the eyes, and a distinctive black spot near the tail.to 20 cm · 1-30 m · by daycoral-rich reefs and rocky slopesOften seen in pairs; look for them inspecting crevices and coral heads for food. (c) Nick Tobler (Cowturtle), some rights reserved (CC BY) · observation
Fire Dartfish (Nemateleotris magnifica)
Fire Dartfish Nemateleotris magnifica A slender, brightly coloured fish with a white body, yellow head and a long, trailing dorsal fin. It hovers above its burrow, darting inside when threatened.to 9 cm · 6-70 m · by daysandy or rubble bottoms near reef slopesLook for a small hole in the sand; the fish will be hovering just above it and will retreat if approached too quickly. (c) Piotr Lukasik, some rights reserved (CC BY) · observation
Whitecheek Surgeonfish (Acanthurus nigricans)
Whitecheek Surgeonfish Acanthurus nigricans A dark brown surgeonfish with a distinctive white patch below the eye and a yellow band at the base of the pectoral fin.to 21 cm · 1-67 m · by daycoral-rich areas of clear lagoon and seaward reefsOften seen singly or in small groups grazing on algae; look for the bright white cheek patch. (c) Piotr Lukasik, some rights reserved (CC BY) · observation
Teardrop Butterflyfish (Chaetodon unimaculatus)
Teardrop Butterflyfish Chaetodon unimaculatus A pale yellow butterflyfish with a single large black spot on its side, a black vertical bar through the eye, and a black-edged tail.to 20 cm · 1-30 m · by daycoral-rich areas of reefs and lagoonsOften seen in pairs; look for them near branching corals where they feed on coral polyps. (c) Piotr Lukasik, some rights reserved (CC BY) · observation