Calling Lake Temescal a destination is a joke. Calling it a place to climb manmade cracks is something that's often mentioned in guidebooks, though in reality it's not an adventure that you're going to want to undertake. The climbing of Lake Temescal and surrounding areas is all manmade. All the "cracks" are portions of old highway supports that now stand unused, and like everything else in the Berkeley and Oakland hills, full of vegetation.
To climb these aformentioned cracks, bring a small spade, a nut cleaning device, and anything else you can think of to remove the vegetation that you will inevidably encounter on your way up the 35' .11 cracks.
There is one excellent (still manmade) exception to the crappy climbing around Lake Temescal regional park: Golden Gate Wall. This 300' gently uphill moving wall contains on hell of a pumpy traverse that will test the endurance of almost anyone.
Going into Lake Temescal will cost you $4 when the gate is manned, which is usually only on weekends. Parking on the street and walking the extra 50 feet is free, but may cost you your stereo (look at all the broken glass on the curbs) and whatever else of value you had sitting around in your vehicle. Parking for The Golden Gate Wall is free, and is across the street from the wall.
The park is open from 7am to sunset, and also offers and excellent opportunity to hang out in the park setting, bike or jog around the small lake, or swim.
Climbing the cracks of Temescal is Illegal by Oakland City ordinance. Due to budget cuts in Oakland, unless you're climbing after hours, you won't get bothered. This is good, until you remember that your car is parked outside of the park, and thieves are also aware of this. If you're climbing after hours, expect a flying circus of Oakland police, probably with guns drawn.
You can buy beer closeby at the Albertson's on College, which is about 1/2 a mile away to the west. From the climbing areas, head downhill (West) on Chabot about a mile until Chabot hits college. Take a left turn, and the Albersons will follow shortly on your right.
The starred section of the Mapquest Map is Chabot Ave and Golder Gate Ave, which is roughly 1/2 a block downhill and North of Golden Gate Wall. The Green section on the rightside of the map is Lake Temescal Regional Park.
From the West:
To Temescal Regional Park:
Take whatever means necessary to get to Highway 24 East. Take 24 to the Broadway exit. Continue stright on the frontage road past the onramp back onto 24, and continue about a 2/3 to the North Entrance to the park, which is a right turn into the parking lot.
To Golden Gate Wall:
Take whatever means necessary to get to Highway 24 East. Take 24 to the Broadway exit. Continue stright on the frontage road past the onramp back onto 24, about 1/3 to a downhill right turn, which is signed as towards Golden Gate Ave. Golden Gate Ave. is a short half block later, and make a right turn downhill heading under the freeway. Parking is on the opposite side of the road from the wall, which is immediately apparent on your right as you head under the freeway.
From the East to Lake Temescal:
Take whatever means necessary to get yourself on Highway 24 West, towards Oakland. This make involve going on 680 if you live in the Eastern Suburbs.
From 24, Take the 13 North exit towards Berkeley. Exit, and continue up to the first light, where you should make a right on Tunnel Road, which will take you back Eastward along the freeway. Continue on the Frontage road (not tunnel road, which makes an abrupt left turn after the light) up and then back down a hill for about a mile, where there will be a sign telling you that 24 East is to the right.
Take this right turn back across the freeway, and instead of going left onto the freeway, go right onto the South frontage road, which will take you downhill about 1.3 miles to the Temescal Regional Park parking lot, which will be a left turn.
From the East to get to Golden Gate Wall:
Continue past the parking lot on the South frontage road about 1/2 a mile West (and downhill) to a left turn, where there is a sign indicating that Golden Gate Wall is to the left. Golden Gate Ave. is a short half block later, and make a right turn downhill heading under the freeway. Parking is on the opposite side of the road from the wall, which is immediately apparent on your right as you head under the freeway.