Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows From Operating Activities
Net income	$ 7,491	$ 13,420
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,012	14,523
Amortization of National Geographic fee	2,180	2,180
Amortization of debt discount, deferred financing and other, net	1,662	2,582
Stock-based compensation	9,464	3,982
Deferred income taxes	(2,017)	(3,709)
(Gain) loss on currency translation	(1,047)	291
Changes in operating assets and liabilities
Inventories and marine operating supplies	(516)	1,505
Prepaid expenses and other current assets	(1,087)	1,098
Unearned passenger revenues	8,062	(8,620)
Other long-term assets	192	(3,159)
Other long-term liabilities	14	22
Accounts payable and accrued expenses	(6,964)	(8,430)
Net cash provided by operating activities	29,446	15,685
Cash Flows From Investing Activities
Acquisition of Natural Habitat, Inc., net of $4,904 cash acquired		(9,946)
Purchases of property and equipment	(44,089)	(50,598)
Redemption (purchase) of restricted cash and marketable securities	311	(1,907)
Net cash used in investing activities	(43,778)	(62,451)
Cash Flows From Financing Activities
Payment of deferred financing costs	(312)	(1,565)
Repayments of long-term debt	(1,312)	(1,312)
Repurchase of employee shares as part of cashless exercise of options or vesting of restricted shares for tax purposes	(1,182)	(2,695)
Repurchase of warrants and common shares	(6,166)	(5,420)
Net cash used in financing activities	(8,972)	(10,992)
Effect of exchange rate changes on cash	204	(128)
Net decrease in cash and cash equivalents	(23,100)	(57,886)
Cash and cash equivalents as of beginning of period	135,416	206,903
Cash and cash equivalents as of end of period	112,316	149,017
Cash paid during the period for:
Interest	7,841	7,427
Income taxes	965	992
Non-cash investing and financing activities:
Additional paid-in capital exercise proceeds of option shares	168	1,123
Additional paid-in capital exchange proceeds used for option shares	$ (168)	$ (1,123)