iPhones are becoming increasingly popular in the outdoors as the technology advances and a plethora of outdoor related aps are available for download.

In the recent issue of Adventure Kayak, writer David Johnston talks about a few of the iPhone aps that are available for download right now.

Aps range from knot guides to nautical charts to aps that transform the iPhone’s internal GPS into a functional GPS handheld.

Here’s a little bit from MotionX-GPS about their GPS ap.

MotionX-GPS HD embeds the functionality of an advanced GPS unit or chart plotter into a intuitive application that is ideal for outdoor activities such as walking, hiking, sailing, off-roading, flying, geocaching or exploring new places.

With worldwide coverage, MotionX-GPS HD enables users to show their current position and track at all times on street, topographical/terrain, satellite, hybrid, or nautical maps.

“With MotionX-GPS HD you can travel the world and access on-board maps everywhere you go,” said Philippe Kahn, founder and CEO of Fullpower.

“This is a huge advantage because you can download maps of any geographic region for free via WiFi without incurring extra data charges.

You’ll have access to maps from Beijing to Honolulu to San Francisco to Paris — literally anywhere you travel around the globe. And with the new address lookup you can also route a path anywhere in the world – point to point as the crow flies.

Reports also indicate that MotionX has just released an iPad version of the software which will benefit from such features as HD display and extended battery life.