A lot of wetsuit/boardshort underlayers are available, including jammers and briefs. At present, this O'Neill is unusual in not having a drawstring, which makes for a non-bulky waistline. Similar options had been available from several surf brands.
Boardshorts that minimize chafing have become widely available, so a brief or possibly a thin neoprene short might be considered (one wetsuit brand is promoting a boardshort that attaches to their neoprene short). The O'Neill I received is TRVLR series, 88% recycled polyester, 12% recycled spandex.
The short has sturdy seams, slightly more of them than most jammers.
The O'Neill "Lycra" short will replace two older shorts, one from Speedo, which no longer has a no-drawstring. Large is a good fit for me; board short size is 34, swimwear 36, wetsuit mostly LS.