Well, water will 'gravitate' along the path of least resistance. And if that is towards your pit, that's where it will go.
I don't think you have an underground stream. They 'exist' in bedrock with 'capillaries' that 'emit' water, again, at paths of least resistance. If you had an underground stream, water in it would have to rise and be FORCED out AND upwards into the ground and eventually towards your pit. I'm no expert on underground streams but I've read about them enough to be 'dangerous'.
From the sounds of it, you might have a sloping problem outside your foundation. You should have a slope of at least 1/4" per foot that's graded AWAY from your foundation, for a distance of at LEAST 3'. If you have relatively flat ground OR if you have soft soil (like a garden where the dirt is 'loose') OR if your downspouts dump their water at the base of your foundation, then all these 'conditions' add to your problem.
Personally, I DO like gardens around the home. But I DON'T like them built right up against the foundation because they prevent air flow, permit water to 'collect', and are always wet. Nothing should be growing or 'extending' within 12-18" of the foundation so as to prevent/minimize the problems I just mentioned. Also, add 3' extensions to your downspouts. (They make flexible ones at the Home Centers in case a 'straight line' won't work for you. Grade the soil so it slopes AWAY from the foundation. And, lastly, check that your gutters aren't leaking, that your gutters aren't allowing water to overflow onto the ground at the foundation, check that the water that runs off the roof actually runs INTO the gutter (and not behind it or over it), and check that you have gutters (and downspouts w/extensions) on rooflines that SHOULD have them. (YOu'll want to put on your boots and raincoat and grab an umbrella the next time you get a sustained rain. Look UP as well as DOWN during the storm to see where the water runs AND/OR collects on the ground. You'd be surprised at what you learn. In my experience, 95% of the causes of water in the basement/crawlspace are due to what I already mentioned. Here's a very good link that talks about the causes and solutions for your problem. Causes Of Water and Moisture In The Basment. Be SURE to read through the 'Next Page' of each section. Eventually, you'll see AAAAAALL the things I've talked about.