Lindblad Expeditions has earmarked $300m in equity as available for possible sale in various forms through a shelf registration.

The Sven-Olaf Lindblad-led owner of expedition cruiseships has filed a prospectus with the Securities and Exchange Commission that will allow it to sell the equity from "time to time" as either debt securities, common stock, preferred stock and warrants.

Equity may also be offloaded as subscription rights, securities purchase contracts and units, according to the regulatory filing submitted on Monday.