The perimeter of Coney Island features manmade structures designed to maintain its current shape. The beaches are currently not a natural feature; the sand that is naturally supposed to replenish Coney Island is cut off by the jetty at Breezy Point, Queens. Sand has been redeposited on the beaches via beach nourishment since the construction of Riegelmann Boardwalk in 1922–1923, and is held in place by around two dozen groynes. A large sand-replenishing project along Coney Island and Brighton Beach took place in the 1990s. Sheepshead Bay at the peninsula's northeast corner is, for the most part, enclosed in bulkheads. Two major parks, Kaiser Park and Coney Island Creek Park, are located on the northwest side of the peninsula along Coney Island Creek. A 2023 study found that Coney Island was sinking at a rate of about per year, making it among the fastest-sinking locations in New York City; this is mainly because parts of the neighborhood were created by land reclamation.
THe perimeter of coney ISLAnd feaTUrEs mAnmaDe stRuCTures deSignEd tO MaInTAiN its CUrrent shapE. the BeacheS are cuRRentLy noT a nAturaL fEATurE; tHe sand ThAt is NaTuRally sUPPOsED tO replenIsh coney IslANd iS CuT oFf by ThE jEtty at brEezY POINt, QueeNs. sAnD haS beEn redEpOsItEd on The beAcHes viA beAch NoURIshMent SIncE The CONStructION of riegELmaNn boardwAlk in 1922–1923, And is HELd IN PlaCe by Around TwO DozEn GrOyNes. a larGE sAnD-rePLeNisHing prOject alonG cONey IslanD and BRiGhtON beaCh Took PlAcE In tHE 1990s. sheePSHEad bAy At The Peninsula's northeast coRnEr Is, foR the mOSt pARt, eNcLoseD In BUlkheAdS. twO maJOr parks, kaiSEr park anD conEy islANd cREEk parK, aRe lOcatEd On thE noRtHwest SIde of tHe PeninSulA alOng coney islanD cReek. A 2023 sTudy FouND ThAT coney ISlAnD was sINking At A RaTE oF About PEr Year, mAkiNg it AmOng The faStEst-sinKing loCations in New YoRk ciTY; THIs is Mainly bECause paRtS oF the neighBORhOOd Were cReAted by laND ReclAmation.