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The Tunnel

Northern Coral Reef: Discover the breathtaking Northern coral reef, nestled along the cliff line in the pristine waters of Bullard Avenue, Dededo, Guam, United States. With its clear waters boasting visibility of up to 15m, this dive site offers an extraordinary underwater experience for divers of all levels - from beginners to advanced.

Schooling Fish and Spectacular Coral Formations: Immerse yourself in a vibrant marine ecosystem teeming with an abundance of colorful schooling fish and awe-inspiring coral formations. Get lost in the beauty of the underwater world as you explore the Northern coral reef.

Natural Opening with Intriguing Depths: Dive into the natural opening in the reef, delighting in a thrilling underwater adventure. Starting at a depth of 35', the reef's intriguing passage gradually ascends to 45'. Along the way, encounter captivating caverns and sand channels, adding an element of excitement to your dive.

Encounter Lionfish and Octopus: Keep a keen eye out for the elusive lionfish within the caverns. Exercise caution and maintain neutral buoyancy at all times to ensure a safe encounter. Additionally, revel in the opportunity to spot the enchanting octopus as they gracefully traverse the reef.

Unforgettable Diving Experience for All: With a maximum depth of 16m, this dive site welcomes divers of all skill levels. Whether you're a beginner eager to embark on your first underwater journey or an advanced diver seeking a new adventure, the Northern coral reef promises an unforgettable experience for everyone.

Optimize your diving escapades with a visit to this remarkable dive site in Bullard Avenue, Dededo, Guam, United States. Immerse yourself in the captivating beauty of the Northern coral reef and create memories that will last a lifetime.

Diving Conditions Score for The Tunnel

6.1
Above Average

Decent conditions, proceed with caution.
The score is based on a calculation of the current weather and sea conditions.

Dive Site Overview for The Tunnel

Depth

16m

Visibility

15m

Experience Level

beginner
advanced

Weather Conditions for The Tunnel

Wave Height

1.28m

Wind Speed

28.6 m/s

Water Temp

29.6°C

Visibility

2.38km

Cloud Cover

100%

Wave Period

6.2s

Air Temperature

25.2°C

Precipitation

0.8 mm

Detailed 7-Day Diving Forecast for The Tunnel
Alpha

Dive Score Chart for The Tunnel

Best time to dive: 7:00 with score 6.0658/10. Water conditions: Waves 1.1m, Wind 20.5 m/s.Best night dive time: 4:00 with score 6.343333333333333/10.

Chart showing hourly dive conditions including wave height, wind speed, water temperature, and visibility throughout the day.

Sunrise at The Tunnel: 06:00
Sunset at The Tunnel: 18:00

Optimal diving conditions at The Tunnel are affected by daylight hours. Sunrise occurs at 06:00 and sunset at 18:00, which impacts visibility and water temperature for scuba diving and snorkeling.

🌙
Best Overall
4:00

Score: 6.3/10
Waves: 1.02m (6.4s), Wind: 19.6 m/s

🌞
Safest Overall
7:00

Score: 6.1/10
Waves: 1.1m (6.05s), Wind: 20.5 m/s

🌞
Best Day
7:00

Score: 6.1/10
Waves: 1.1m, Wind: 20.5 m/s

Seasonal Analysis for The Tunnel
Alpha

Historical patterns and best seasons for diving at The Tunnel

The dive score combines all factors to rate overall diving conditions throughout the year. Higher scores indicate better diving conditions.

Monthly Dive Score Analysis - Seasonal Diving Conditions

Higher values indicate better diving conditions

Seasonal DiveScore Chart

This chart displays monthly diveScore data throughout the year, showing seasonal patterns. The data is presented as a bar chart with an overlaid line graph.Dive scores range from 1 to 10, with 10 being optimal conditions.

Higher values indicate better diving conditions

Best Season for The Tunnel

Winter

Avg. Score: 9.3/10

Winter offers the best overall diving conditions with calmer seas and better visibility, despite cooler temperatures.

Best Months for The Tunnel

February
Score: 9.4
January
Score: 9.3
March
Score: 9.2

Ideal Conditions for The Tunnel

Water Temp

Thermometer Emoji

27.1°C / 80.8°F

May

Visibility

Telescope Emoji

10.5m / 34.4ft

May

Wave Height

Wave Emoji

1.6m / 5.2ft

September

Wave Period

Wave Emoji

8.0s

January

Seasonal Insights for The Tunnel

The Tunnel shows typical northern hemisphere patterns with June being the warmest month (27.3°C) and January the coldest (22.4°C). The calmest conditions typically occur in September with average wave heights of 1.6m and wave periods of 8.0s. The most comfortable wave conditions are in September with a low wave steepness ratio, creating gentler swells. January offers the longest wave periods (8.0s), creating more comfortable and predictable conditions for boat entries and exits. Ocean currents are slowest in January (0.5m/s) and strongest in January (0.5m/s). February is usually the driest month with 1.1mm of precipitation. For beginners, the best time to visit would be during September to November, when ocean conditions are calmer with long-period waves and currents are typically weaker. Experienced divers might enjoy the challenges and potentially better visibility during the shoulder seasons, with moderate currents that can improve marine life encounters.

Scoring Legend:
9-10 (Excellent)
7-8 (Good)
5-6 (Average)
3-4 (Poor)
1-2 (Dangerous)

Last updated: 1 min. ago - Jun 18, 2026

Note: This dive site is not a verified dive site. Please dive with caution. This dive site might have incorrect information by the community.

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