Mercer Beach (also mapped as E. V. Mercer Beach) is a small city park and swimming beach owned by the City of Walled Lake, on the north shore of Walled Lake in Oakland County, Michigan. The city assembled it from several lakefront parcels, including a beach the Mercer family already ran, and named it for E. V. Mercer, who owned and managed the local Home Telephone Company from 1920. A Michigan Natural Resources Trust Fund grant in 1998 paid for a rebuild that wrapped up in the spring of 2000. Walled Lake itself is a glacial kettle lake of about 670 acres, split between the cities of Walled Lake and Novi.

The beach sits on East Walled Lake Drive about a quarter mile east of Pontiac Trail, right at the edge of downtown Walled Lake. Coming from Pontiac Trail, turn east onto East Walled Lake Drive and follow the shoreline past the lakeside restaurants; the beach is on the lake side of the road behind a green iron fence and an arched entrance gate. A small surface lot is mapped beside the beach, and downtown streets and Riley Park are a few minutes' walk to the west. On hot weekends the beach fills up quickly, so arriving early helps.

The city lists about 200 feet of sandy frontage. Michigan DNR survey work cited for the lake describes the shallow bottom as mostly sand and marl, with soft peat out in the deep basin, which reaches about 53 feet. The swim area is marked by buoys that city crews set out for the summer and pull at the end of the season, and portable restrooms are on site from Memorial Day to Labor Day. There is no lifeguard on duty at any time, so children need an adult watching them in the water. As a fairly large, busy lake, Walled Lake carries pontoons, ski boats and personal watercraft outside the buoy line; stay inside the marked area.

Entry is free. The city's park sheet lists no admission or parking charge and no resident-only restriction, and the beach is open to the general public. Posted rules are short: no boats launched from the beach, no pets, and don't feed the waterfowl. The city has closed the beach before when it got too crowded, and has discussed gates so it can be locked after hours, so obey any posted closure or hours sign at the entrance. Hours are not published online; treat it as a daytime beach.

Michigan posts beach bacteria test results, advisories and closures in its BeachGuard system, which is worth a look after heavy rain. Canada geese are common on this shoreline, which is part of why the no-feeding rule exists. Besides the sand and the water, the park has picnic tables, benches, a drinking fountain and a boat-themed playground for small kids. A lakeside bar and grill, an ice cream shop and the rest of downtown are a short walk west along East Walled Lake Drive, and Riley Park, the city's small downtown park with its own playground, is a couple of blocks away.