Top 10 Factors Affecting Dive Visibility: AI Impact Ranking Analysis

What single factor most predicts tomorrow's visibility? Not the weather — it's yesterday's water temperature change. Here are the top 10 factors our AI discovered from 46,000+ observations.

Impact Ranking

The chart below shows how heavily the AI model relies on each factor when making predictions. Higher values indicate that the model considers that factor more critical to its predictions.

Breakdown of Each Factor

#1: Water Temperature Change (1-Day) — Importance 778

The single most important factor is the day-over-day change in water temperature. Days with sharp temperature swings tend to see large visibility shifts as well. This metric serves as a proxy for ocean current changes. For example, when a warm-water mass from the Kuroshio Current approaches, water temperature rises abruptly and clear offshore water moves in. Conversely, upwelling events bring nutrient-rich deep water to the surface, fueling plankton growth and reducing visibility. For divers, a temperature increase from the previous day is often a sign of improving visibility.

#2: Previous Day's Visibility — Importance 681

It is intuitively unsurprising that yesterday's visibility ranks second. Ocean conditions rarely change dramatically in a single day; the previous day's state tends to carry over. That said, exceptions do occur — after typhoons or heavy rainfall, for instance — and the model captures these sudden shifts by combining this feature with others.

#3: Visibility Variability (7-Day) — Importance 572

The standard deviation of visibility over the past seven days ranks third. This metric reflects the stability of ocean conditions. Periods of high variability indicate volatile currents and weather, which tend to produce unpredictable visibility. The model has learned that when good visibility holds steady over several days, the following day is likely to be favorable as well.

#4: Diffuse Attenuation Coefficient (Satellite Data) — Importance 542

Kd490 is a light diffuse attenuation coefficient derived from satellite observations via NOAA ERDDAP. It reflects the concentration of suspended particles and phytoplankton in the water column. Higher values indicate more particulate matter and, consequently, lower visibility. Incorporating satellite data allows the model to account for broad-scale oceanic changes that local observations alone cannot capture.

#5–6: Moving Average Visibility (7-Day & 3-Day)

The 7-day and 3-day moving averages of visibility rank fifth (444) and sixth (425), respectively. Beyond just the previous day's value, tracking multi-day trends allows the model to determine whether conditions are improving or deteriorating. A large gap between the 3-day and 7-day averages can signal an inflection point in the trend.

#7: Longitude — Importance 368

Longitude appears as an important factor because Japan's dive sites are spread across a wide east-west range. The Pacific coast and the Sea of Japan coast are governed by fundamentally different current systems — the Kuroshio on the east and the Tsushima Current on the west — resulting in distinct visibility patterns.

#8: Visibility Change (1-Day) — Importance 367

The magnitude and direction of change from two days ago to the previous day is also significant. Capturing whether visibility is on an upward or downward trajectory helps the model refine its next-day forecast.

#9: Water Temperature — Importance 356

Water temperature itself is a meaningful indicator. In general, the cooler winter months bring higher visibility, while warmer summer waters promote plankton activity and reduce clarity. However, sites like Ishigaki Island maintain excellent visibility even at high water temperatures, illustrating the complex interplay between temperature and regional characteristics.

#10: Latitude — Importance 351

Like longitude, north-south position matters. Low-latitude sites in Okinawa tend to maintain consistently high visibility, while sites in northern Honshu experience stronger seasonal fluctuations — a geographic pattern the model has internalized.

Practical Advice for Divers

These findings point to several actionable takeaways for divers looking to gauge visibility. First, check the previous day's visibility and water temperature change. A dive shop's daily log is the most reliable source of information.

Second, track the multi-day visibility trend. If good conditions have held steady for several days, the next day is likely to deliver as well. Third, be prepared for rapid visibility changes whenever there is a sudden shift in water temperature. By combining these signals, you can choose the best days to dive and maximize your chances of clear water.