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Harley Reef

Harley Reef is an ideal dive site for beginners and experienced divers alike. Situated along the breakwater wall in Apra Harbor, United States, the Harley itself sits at a depth of approximately 15 feet. With a gradual slope leading down to a maximum depth of 17 meters (110 feet), this site offers a captivating underwater experience for all levels of diving expertise. Nearby attractions include the Val Bomber and Barge Reef, both worth exploring.

One of the highlights of diving at Harley Reef is the frequent sightings of Green and Hawksbill Sea Turtles. To observe these magnificent creatures, it is important to move slowly and refrain from touching or pursuing them. Maintaining neutral buoyancy is crucial for a better turtle-watching experience.

To fully immerse yourself in the beauty of this site, consider drifting towards the mouth of the harbor. This will provide an opportunity to encounter intriguing underwater relics such as antique coke bottles, octopus, and occasionally, turtles. It is advisable to be mindful of the wind direction when surfacing, ensuring ample time to return to the boat away from the breakwater wall.

With a visibility of approximately 12 meters, Harley Reef offers clear views of its rich marine life and captivating underwater landscape. Whether you're a beginner or experienced diver, don't miss the chance to explore this remarkable dive site in Guam.

Diving Conditions Score for Harley Reef

6.5
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 Harley Reef

Depth

17m

Visibility

12m

Experience Level

beginner

Weather Conditions for Harley Reef

Wave Height

3.1m

Wind Speed

9.3 m/s

Water Temp

28.9°C

Visibility

2.44km

Cloud Cover

100%

Wave Period

10.05s

Air Temperature

26.6°C

Precipitation

0.7 mm

Detailed 7-Day Diving Forecast for Harley Reef
Alpha

Dive Score Chart for Harley Reef

Best time to dive: 17:00 with score 5.956033333333333/10. Water conditions: Waves 2.96m, Wind 10.6 m/s.Best night dive time: 19:00 with score 5.648666666666667/10.

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

Sunrise at Harley Reef: 06:00
Sunset at Harley Reef: 18:00

Optimal diving conditions at Harley Reef 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
17:00

Score: 6.0/10
Waves: 2.96m (10.05s), Wind: 10.6 m/s

🌙
Best Night
19:00

Score: 5.6/10
Waves: 2.88m, Wind: 5.8 m/s

Seasonal Analysis for Harley Reef
Alpha

Historical patterns and best seasons for diving at Harley Reef

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 Harley Reef

Winter

Avg. Score: 9.4/10

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

Best Months for Harley Reef

January
Score: 9.5
February
Score: 9.4
November
Score: 9.4

Ideal Conditions for Harley Reef

Water Temp

Thermometer Emoji

27.6°C / 81.7°F

May

Visibility

Telescope Emoji

11.2m / 36.7ft

November

Wave Height

Wave Emoji

1.4m / 4.6ft

September

Wave Period

Wave Emoji

8.0s

January

Seasonal Insights for Harley Reef

Harley Reef shows typical northern hemisphere patterns with May being the warmest month (27.6°C) and January the coldest (22.7°C). The calmest conditions typically occur in September with average wave heights of 1.4m 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 1.0mm 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 - Jul 8, 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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