Apart from the bay area, there are several other hiking and trekking spots in San Francisco.
Here are the top 5 San Francisco hiking and trekking tour providers:
1. Footloose Forays - These are basically educational trips into natural world, featuring wide range of expeditions from day trips to three week adventures, which may be near your backyard or take you into another hemisphere. Some of these are for the energetic youngsters, while there are many for those who love slow and easy-going stuff. They're good for adults, as well as for the entire family.
2. Getaway Adventures - The entire staff of this company is local, and each of them are well aware of the flora and fauna of the San Francisco area, hence they can tell you the minutest detail about every nook and corner during the hiking and trekking trips.
3. Back to Earth - It is a great community space to enjoy natural world, scenic beauty and feel the thunder of trekking in SF.
4. Sonoma TrainTown - It is renowned as the most well-developed scale railroad in America.
5. Access Adventure Travel Ltd. - It is one of the very few companies that specialise in providing instructional adventure tours. It is a perfect option for those who're looking for a blend of adventure, fun, simplicity and natural beauty in their hiking and trekking tour. You can get unique and memorable travel experience with these trips, along with a fair deal of instructional guidance.
You can find many more providers here:
http://www.bnbstar.com/vdosearch.asp?command=search&selstate=6&area=&selcity=San%20Francisco