I'm going to start you on Al Madinah Road (271) going north from Al Balad. Red Sea to the left, Mecca to the right. You'll be on this road for a while, so be patient.
Look for signs pointing towards Madinah and/or the airport.
You're heading the right way.
Pass Mall of Arabia on your right...
...then pass the airport...
...and keep following the signs for the Obhur (Northern) District.
This is the exit you want to take (the second one after going under the bridge). The first one (before the bridge) takes you to the stadium.
This stadium (King Abdullah Sports City). Keep an eye out for it on your right.
Go under the bridge, then loop back around and go over the bridge.
Then you'll come to this traffic circle with these cool-looking camels. Take the FIRST exit after entering the circle. It comes up pretty quick, so stay to the right and pay attention. This road, Prince Abdullah Al Fiasal Street, will take you over to the coast and the beaches.
You'll pass Batterjee Medical College on the right...
...this tower-thingy on the left...
...Red Sea Marina on the left...
...and this tower on the left. This is about where the road starts to turn right (north) and the beaches will be coming up on your left.
Look for this minaret with the green top, the entrance to Al Murjan beach will be right there on the left. You'll have to pass it then do a u-turn to go back to it. If you want to go to Silver Sands, keep going...
...through this circle...
...past Bhadur Resort (Turkey Gholam Beach is right next to this one. I don't recommend it though.)...
...through this circle with palm trees and a pink mosque...
...until you get to the Sheraton Resort on your left.
Go past the Sheraton entrance along this white wall...
...and the first, big, blue gate is the entrance to Silver Sands Beach. Bang on the smaller door to the left or there might be a ringer hanging from the wall. Be patient. Someone will come out to ask if you're a member, where you're from, what you do, etc. Not sure exactly who is allowed to go in, but my wife and I just show our passport/passport copies and say we teach at a university here and they let us in.
It's now 150 SAR per day for adults - up from the 100 SAR I paid in the spring. After going in the spring, I was told that next time I had to be a member to enter. They didn't stick to their word. So give it a shot!
So that's how I get to the Jeddah beaches I've been to (Silver Sands, Al Murjan, and Turkey Gholam). You can probably take one of the exits after the stadium on Al Madinah Road, but I just stick to this route because it's the first way I learned. There are other beaches all along that coastal road - some where you can bare most and other beaches for locals where (I believe) the women have to cover. Just knock on some doors and talk to people and you'll probably find others.
Contact me or comment with any questions or suggestions and good luck out there!
P.S. - A few other tips:
- Watch your speed. There are speed cameras along the two main roads you take (going there and coming back). I got a 300 SAR fine one time.
- Avoid the fast lane unless you enjoy the crazy drivers who pass you on the left (on the shoulder) and almost take off your side mirror.