If we lived on a planet similar to Earth with the same lengths for day and night - but the entire planet was covered (at some point in the year) by water, could civilisations exist and prosper as they have on Earth?
My visualisation of this planet is something similar to Earth except it is entirely covered in water at some point in the year, but a force other than the sun continuously pulls the tides around the planet. The tide takes an entire year to come around fully, so there would be a few months on any point where there would be no ocean, then it would be submerged for a few months when the tide comes back around. There is a lot of water on this planet but a large gravitational force is able to keep nearly all of it moving, leaving only some lakes in the imperfections of the land. While there is a lot of water, the slow-moving nature of it doesn't erode away the land extremely quickly as it just slowly moves around the entire planet. Perhaps a moon that somehow moves very slowly can create this force. When the water is on part of the planet it can range from being a few metres deep to up to half a kilometre, and when the "tide" has been gone for a few weeks the surface could appear very dry again depending on the distance to the equator.
Assuming human life has managed to evolve on this planet, would it be possible for them to build a long-lasting civilisation in this world - perhaps a maritime nation with no stationary home but a constantly moving fleet, or would the constant moving and difficulty to find resources and forge technology simply make this too hard to form civilisations?