Try this:
else {
$body = "Date: $date\n",
$body .= "Dive Site Location: $dive_site\n",
$body .= "Depth: $depth\n",
$body .= "Additional Information: $additional_information\n",
mail ( "larissahn@rocketmail.com", "Report Lionfish Sighting Form",
$body,
"From: $name " ) ;
http://php.net/mail