The term "deep pool" is commonly used in finance and economics to describe a situation where there are significant amounts of capital available for investment, leading to lower costs of capital. This can occur when there is an abundance of savings or credit in the economy, which allows businesses and individuals to borrow money at relatively low interest rates. In contrast, during periods of economic downturns or recessions, the deep pool of funds may dry up, leading to higher costs of capital as investors become more risk-averse and demand higher returns for their investments.