Very nice site!
Regarding you question, I presume the submenu is done with showmenu2(). Based on the info on
http://www.websitebakers.de/sm2/media/README.en.txt, I guess you can just put the anchorname after the link in the
$aItemOpen part. If your anchor is #holedescription, use a showmenu like:
show_menu2(
$aMenu = 0,
$aStart = SM2_ROOT,
$aMaxLevel = SM2_CURR+1,
$aOptions = SM2_TRIM,
$aItemOpen = '[li]<a href="[url]#holedescription">[menu_title]</a>',
$aItemClose = '</li>',
$aMenuOpen = '[ul]',
$aMenuClose = '</ul>',
$aTopItemOpen = false,
$aTopMenuOpen = false
)
Not tested!