Speedometer is leaking water??

So, my friend has a 2001 Ski-Pro Extreme. We took it out this weekend, and at high speeds (25-40mph)the gauge would partially fill with water and leak straight from the face of the gauge. I thought it was water that leaked into the dashboard during storms, and it found it's way out. My friend thinks it may be something with the speedometer cable?

Has anyone seen this? What could be the cause?

Thanks