On 1 servers with real players. Checked 16:27 UTC.
surf_underworld is a surf map: you slide along sloped ramps instead of running. It is not one of the maps that come with the game, so servers send it to players from the Workshop when they join.
Over the last 30 days surf_underworld was the #3306 map on CS2 community servers, with <1 real players on it at any moment on average - 0% of everyone playing. It ran on about 0 servers with real players at a time. Right now 1 people play it on 1 servers, most of them on servers in the United States. It is busiest on Wednesday around 19:00 UTC and quietest on Monday around 00:00 UTC.
Right now 1, on 1 servers from the Steam server list. Over the last 30 days it had <1 real players on average at any moment. Fake servers and bots are not counted, and Valve matchmaking is not in the list.
On Wednesday around 19:00 UTC. The grid above shows every hour of the week in your own time zone.
The busiest right now: [LocalsOnlySurf.Net] VIP Surf [US-East] (1 players). The full list is under "Servers running it now", and every server has its own page with its history.
de_mirage43,336 players on average
de_dust217,901 players on average
sandstone_fb14,483 players on average
de_mirage_fps6,349 players on average
awp_lego_25,451 players on average
awp_lego_2_fb4,852 players on average
de_mirage_christmas2,858 players on average
<null>1,275 players on average
bhop_emevaelx31,054 players on average
duels_mirage_1x11,010 players on average
de_inferno889 players on average
de_nuke764 players on average
US