* Refraction: When light passes from air to water, it bends. This bending, called refraction, makes objects underwater appear closer to the surface and in a slightly different position than they actually are. So, you're aiming at an image that's shifted, leading to an inaccurate throw.
* Air resistance: The air slows down the object as it travels, and this slowing down isn't uniform. This means the object won't follow a perfect straight line, which can lead to it landing slightly off-target.
* Your own throw: Even if you aim perfectly, your throw itself might not be perfectly straight. This is especially true if you're not used to throwing things accurately.
Here's a simplified analogy: Imagine you're trying to shoot a basketball into a hoop. If the floor is slippery, the ball won't travel in a straight line, even if you aim perfectly. In the same way, the water's surface, air resistance, and your own throw all act as "slippage" that makes the object land off-target.
It's a combination of these factors that makes it tricky to throw something precisely into a lake.
