No Guts, No Glory Achievement
No Guts, No Glory15
Perform a 2.5 second or longer swan dive
This achievement will come naturally in the course of working towards the challenges in the Geothermal Valley region, which include completing four dives from a high location. One of these will take place near to the Ridgeline base camp and take longer than the 2.5 seconds required for this achievement to complete. Look for a board above the waterfall a short distance from the camp; once you've found it, sprint towards the board and jump then dive (with quickly after jumping) as you reach it.
Here's a video guide taken from YouTube: