They have a 30-day volume of 150,000 BTC. That's a quarter of Bitfinex/Bitstamp. But what I wonder is if they are credible.

LakeBTC is one of the ‘Big Four’ exchanges that decide the ‘Bitcoin Price Index’ of CoinDesk. Anybody has ever used it? Are they legitimate?

Dark pool is a good way to  avoid trigger volatility and protect general traders.