Why some low tides are better

Two lows a day, every day, but only a handful each month are worth getting up for. Three cycles decide which ones.

Springs and neaps

When the sun and moon line up, around new and full moon, their pulls add together and the tides swing furthest: high highs and low lows. These are spring tides (nothing to do with the season). A week later, at the quarter moons, the range shrinks to neap tides, and the lows hardly uncover anything. The best lows usually come a day or two after new or full moon.

The uneven pair

Singapore's tides mix a twice-daily rhythm with a once-daily one, so each day's two lows differ. For part of the year the lower of the pair falls before dawn, and for part of the year in the afternoon or evening.

The time of year

Putting those together, here is how the good lows fall across the months in my calendar, split by whether they come in daylight:

The very lowest tides of the year tend to come around dawn in the middle of the year, which is why so many shore walks start in the dark with headlamps.