Spotted a red-and-white vertically striped buoy while out on a lake? Good news: that's a safe water marker, telling you the water around it is deep enough to pass without grounding your boat. It's part of the international Aids to Navigation (ATON) system run by IALA, which standardises the colours, shapes and patterns that guide boats much like road signs guide cars.

In the United States, water markers fall into five categories: lateral, cardinal, isolated danger, safe water and special. The red-and-white buoy belongs to the safe water family. You'll usually find it marking channels, keeping boaters in the deepest, safest part of a waterway. Water on either side is navigable, but the convention is to pass on the port side — the left, when you're facing the bow.

These buoys come in spherical, pillar or spar shapes, topped with a single red round mark, and often a white flashing light. Under IALA rules there are three variants, distinguished by the number of vertical stripes: eight, six or four. So if you count the stripes, you're not just being curious — you're reading the sign.

One wrinkle worth knowing: big lakes like the Great Lakes follow the same IALA guidelines used on oceans, but smaller inland lakes may run on regional rules that broadly align yet can differ. A quick check of local regulations before you launch saves confusion later. That's especially relevant in a country with more than 100,000 lakes to explore, from fall-foliage classics in the Northeast to deep-water spots like Lake Chelan in Washington state.

For holiday travellers, this isn't trivia for the sake of it. Renting a pontoon, kayak or canoe on a lake trip means you're suddenly the person responsible for reading the water. Knowing that red-and-white stripes mean safe passage, and that black-and-white striped markers carry a different message, makes a day on the lake more relaxing — you can trust the markers instead of guessing. It's the boating equivalent of knowing what a yellow traffic light means before your first drive abroad.

The broader takeaway: water markers are a language, and a few minutes of learning the basics pays off wherever you rent a boat — a lake in New York, a reservoir in California, or coastal waters overseas. Safe Boating America and IALA both publish straightforward guides, and many rental operators will walk you through local markers before handing over the keys. Ask them; it's the fastest way to get fluent.

Bottom line: a red-and-white striped buoy is a welcome sight, not a warning. Pass on either side, favour port, and enjoy knowing you're in the deep, safe channel. — Islands