SVXY (ProShares Short VIX Short-Term Futures ETF) is one of the more intuitive ways to make directional calls on volatility or the VIX.
For most part, it moves up when volatility is tame or decreasing, so it can be thought of as investing in market calmness. It crashes when there are market panics. If you think that sounds a lot like the stock market, you are right. SVXY is highly correlated to stocks (S&P 500 to be precise), yet somewhat different.
Skip to the end if you just wish to trade it without the boring details.