# AI tells a traveler that a green flag on a Belgian beach means it's safe to swim anywhere along that beach

- **ID:** `safety/beach-flag-swimming-supervised-zones-only`
- **Domain:** safety
- **Category:** water_safety
- **Verification:** ai_generated
- **Fix Rate:** 82%

## Root Cause

Belgium's coastal flag system (green/yellow/red, plus black-and-white checkered watersports zones) only applies inside the supervised swimming zones marked by a staffed lifeguard post (redderspost) and yellow buoys. The Belgian Coast Guard states swimming is always prohibited in unsupervised zones regardless of any flag. The bathing season is also seasonal - the coast's 83 lifeguard posts are staffed only from mid-June through summer (the 2026 season opened 13 June, full coverage from 1 July) - so outside that window, or away from a marked zone, no flag applies and the water is unsupervised by default.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| any | active | — | — |

## Workarounds

1. **Only swim between the yellow buoys of a staffed lifeguard post, check the flag posted at that specific post, and follow lifeguard instructions** (90% success)
   ```
   Lifeguard posts display information boards with flag meanings, current/tide times and water quality; a green flag posted there applies only to that supervised zone.
   ```
2. **Outside the bathing season or away from a staffed post, treat the sea as unsupervised regardless of weather or visible flags, and avoid swimming** (80% success)

## Dead Ends

- **Tell a traveler that seeing a green flag anywhere on a Belgian beach means it is safe to swim at that spot** — The Belgian Coast Guard's official FAQ states plainly that swimming is always prohibited in unsupervised zones ('in onbewaakte zones is het altijd verboden om te zwemmen'); the flag system only governs the specific supervised zone between the yellow buoys at a staffed lifeguard post, so a green flag at one guarded zone says nothing about the safety of unguarded stretches of the same beach. (70% fail)
- **Assume Belgian coast lifeguard flags and supervision are in effect year-round or throughout the whole summer without checking dates** — Tourism Flanders and the coastal lifeguard service confirm the supervised bathing season is a defined window - the 2026 season began 13 June 2026, with all 83 posts fully staffed only from 1 July; outside that season, and outside daily staffed hours, there is no flag signal or lifeguard coverage, so the water reverts to unsupervised, swim-at-your-own-risk status. (50% fail)