179
xkcd #3248: 182.8 Meters
(imgs.xkcd.com)
Title text:
They rounded down to 182.8 instead of rounding up to 182.9 because 182.9 might make the statement incorrect.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3248/
Or currents might deepen a hole too. Putting silt in one place can cause other places to change too.
And if it were more shallow, shipping would have a big impact too.