Whenever a crocodile came within a quarter mile of the receptor, the movement was recorded. After a year of monitoring the reptiles along the river, the scientists discovered that they habitually travel from their home area to the river mouth, a distance upwards of 31 miles away.
Whenever the gigantic beasts traveled more than 6 miles a day, they surfed. The crocs always started their journey immediately after the tides turned, securing them a solid 6 to 8 hours of speedy travel.
Every time the tides changed to an unfavorable direction, the crocodiles took a rest stop. They retreated to the nearby shore for a period of hours to days.
As a short term solution to unfavorable tides, the animals would dive to the bottom of the river, where they can spend up to an hour lounging on the river floor, rather than moving back to land.
In a previous study, the researchers outfitted three crocodiles with satellite transmitters. This allowed the team to follow the "salties" - the Australian nickname for the predators - beyond the river mouth and into the ocean.