I'm pretty sure I found it and it's called Shark Attack 3: Megalodon. Here's a review on Amazon:
Success! Megalodon gets it right!, February 13, 2006
This quite simply may be the best "bad" movie of the last 10 years. No debate here between 1 star because it's so poorly done and 5 stars because it's so deliciously bad; it's a 5 star movie, no question. Continuity, quality props, editing, horrible dialogue and scale mean nothing in this movie. No mention of the plot in this review, it's secondary. When you can literally laugh out loud at events because they are so poorly done with total disregard for the viewer, this B-movie is a must see and worth 94 minutes of your life.
The funniest scenes for me are when boats are supposed to be speeding along the shore and then in close ups of the actors, the background is not moving, no wind, no boat vibration, absolutely stationary. And not just once, this methodology is used for every boat scene irregardless of the boat, time of day or actors involved. You can't miss it. And they keep jamming the main boat into full throttle without ever shifting it into a lower speed position. Look we're in low, jam it into high. Look we're in low again some how, jam it into high. Look we're in low yet again, jam it into high. Over and over again. Quality entertainment, guaranteed.
When the Megalodon first appears and eats a boat whole, it's hysterical. Gulp, it's over. You're thinking "What the heck just happened?" Then two guys in the water: gulp, it's over. A raft full of a dozen people: gulp, it's over. A guy jumps off a boat and swan dives into the Megalodon's wide open mouth; gulp, it's over. A jet ski traveling at high speed: gulp, it's over. All of varying sizes and all barely fitting into the giant sharks mouth. The reuse of stock shark footage over and over again is quite entertaining.
In the final act, the Megalodon is attacking a large yacht and it's panicked passenger are doing what?.... they are jumping INTO the water! What? Why? The boat isn't sinking and there's 75 feet of body chomping carnage IN THE WATER anyway. Talk about people deserving to die.
Despite enormous plot holes, haphazard editing, meaningless scenes, unbelievable characters ("What did he just say?") and bad acting, this movie just plows on and like the Megalodon, nothing can stop it. Combined with a gratuitous sex scene and well placed nudity throughout, it's a must see. If you're a B-movie, schlock, sci fi horror junkie, it's a 5 star movie. Don't miss it. | 
