It's hard to accept that the battle where, up to now (except for God Valley), the most high-level characters fought together, the largest number of armies in the series so far, with several Logia users, took place in a field with a maximum circumference of 1km (if you consider the dimensions of San Juan) and that would fit on Loki's back if you were measuring pixels.
If we're measuring pixels, an average person, like you reading this, could walk from the beginning to the end of Marineford in a maximum of 20 minutes. It took several hours for Ace to be rescued and for the entire battle in that place, with its many island-destroying characters, to be completed.