What’s the equivalent of the expression “still waters run deep” in the foreign exchange market?

I’m not sure but I know that sometimes the most-quiet markets are the ones that need to be watched most-closely. USD/CAD has been in a 30-pip range (and narrowing) for the entirety of North American trading.

The top came on the drop in oil and the bottom came as risk trades/Brazil improved but the market has been lazy since.

USDCAD 10 minute wedge

USDCAD 10 minute chart

A break in either direction is probably worth 20 pips but betting on USD/CAD volatility in Asia-Pacific trading is often a bad bet.