If you will use google earth and look to the east of Bermuda you will see much more of these lines but in starker relief. What you are seeing is the result of spreading and faulting along the Mid Atlantic ridge which is a spreading center for the earth’s crust. The reason they are not as evident to the West of Bermuda is sediment deposition off the North American Continent.
That doesn’t explain the hairpin turns, or the fine lines.
I was thinking that the wider lines are areas where the sea floor was deliberately mapped in higher definition, since none of them look natural and they are usually in better focus than the surrounding area.